Q: Extract the answer to the question from the following context. Question: How can one tell if a scientific hypothesis is properly structured? Context: Logically, no number of positive outcomes at the level of experimental testing can confirm a scientific theory, but a single counterexample is logically decisive: it shows the theory, from which the implication is derived, to be false. To say that a given statement (e.g., the statement of a law of some scientific theory) -- [call it "T"] -- is "falsifiable" does not mean that "T" is false. Rather, it means that, if "T" is false, then (in principle), "T" could be shown to be false, by observation or by experiment. Popper's account of the logical asymmetry between verification and falsifiability lies at the heart of his philosophy of science. It also inspired him to take falsifiability as his criterion of demarcation between what is, and is not, genuinely scientific: a theory should be considered scientific if, and only if, it is falsifiable. This led him to attack the claims of both psychoanalysis and contemporary Marxism to scientific status, on the basis that their theories are not falsifiable.
A: a theory should be considered scientific if, and only if, it is falsifiable

Q: Extract the answer to the question from the following context. Question: How can a prisoner delay his execution? Context: Traditionally, Section 1983 was of limited use for a state prisoner under sentence of death because the Supreme Court has held that habeas corpus, not Section 1983, is the only vehicle by which a state prisoner can challenge his judgment of death. In the 2006 Hill v. McDonough case, however, the United States Supreme Court approved the use of Section 1983 as a vehicle for challenging a state's method of execution as cruel and unusual punishment in violation of the Eighth Amendment. The theory is that a prisoner bringing such a challenge is not attacking directly his judgment of death, but rather the means by which that the judgment will be carried out. Therefore, the Supreme Court held in the Hill case that a prisoner can use Section 1983 rather than habeas corpus to bring the lawsuit. Yet, as Clarence Hill's own case shows, lower federal courts have often refused to hear suits challenging methods of execution on the ground that the prisoner brought the claim too late and only for the purposes of delay. Further, the Court's decision in Baze v. Rees, upholding a lethal injection method used by many states, has drastically narrowed the opportunity for relief through Section 1983.
A: not attacking directly his judgment of death

Q: Extract the answer to the question from the following context. Question: If there is atmospheric oxygen present, we know that there cannot be what? Context: In the absence of atmospheric oxygen (O2), in deep geological conditions prevailing far away from Earth atmosphere, hydrogen (H2) is produced during the process of serpentinization by the anaerobic oxidation by the water protons (H+) of the ferrous (Fe2+) silicate present in the crystal lattice of the fayalite (Fe2SiO4, the olivine iron-endmember). The corresponding reaction leading to the formation of magnetite (Fe3O4), quartz (SiO2) and hydrogen (H2) is the following:
A: hydrogen (H2)

Q: Extract the answer to the question from the following context. Question: Which type of metal does not cause toxic symptoms? Context: In 1982, the US Mint began minting pennies coated in copper but made primarily of zinc. With the new zinc pennies, there is the potential for zinc toxicosis, which can be fatal. One reported case of chronic ingestion of 425 pennies (over 1 kg of zinc) resulted in death due to gastrointestinal bacterial and fungal sepsis, whereas another patient, who ingested 12 grams of zinc, only showed lethargy and ataxia (gross lack of coordination of muscle movements). Several other cases have been reported of humans suffering zinc intoxication by the ingestion of zinc coins.
A:
copper