In this task, you are given a question and a context passage. You have to answer the question based on the given passage.

[Q]: The most heat-treatable alloys are decided but only?, Context: Conversely, most heat-treatable alloys are precipitation hardening alloys, which produce the opposite effects that steel does. When heated to form a solution and then cooled quickly, these alloys become much softer than normal, during the diffusionless transformation, and then harden as they age. The solutes in these alloys will precipitate over time, forming intermetallic phases, which are difficult to discern from the base metal. Unlike steel, in which the solid solution separates to form different crystal phases, precipitation hardening alloys separate to form different phases within the same crystal. These intermetallic alloys appear homogeneous in crystal structure, but tend to behave heterogeneous, becoming hard and somewhat brittle.
[A]: Conversely


[Q]: Which trade route connected Northern Europe and Northwestern Russia with the Capsian Sea?, Context: The new Kievan state prospered due to its abundant supply of furs, beeswax, honey, and slaves for export, and because it controlled three main trade routes of Eastern Europe. In the north, Novgorod served as a commercial link between the Baltic Sea and the Volga trade route to the lands of the Volga Bulgars, the Khazars, and across the Caspian Sea as far as Baghdad, providing access to markets and products from Central Asia and the Middle East. Trade from the Baltic also moved south on a network of rivers and short portages along the Dnieper known as the "route from the Varangians to the Greeks," continuing to the Black Sea and on to Constantinople. Kiev was a central outpost along the Dnieper route and a hub with the east-west overland trade route between the Khazars and the Germanic lands of Central Europe. These commercial connections enriched Rus' merchants and princes, funding military forces and the construction of churches, palaces, fortifications, and further towns. Demand for luxury goods fostered production of expensive jewelry and religious wares, allowing their export, and an advanced credit and money-lending system may have also been in place.
[A]: Volga trade route


[Q]: Which of the following is always present in invetebrates, a nerve or a brain?, Context: The brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. Only a few invertebrates such as sponges, jellyfish, adult sea squirts and starfish do not have a brain; diffuse or localised nerve nets are present instead. The brain is located in the head, usually close to the primary sensory organs for such senses as vision, hearing, balance, taste, and smell. The brain is the most complex organ in a vertebrate's body. In a typical human, the cerebral cortex (the largest part) is estimated to contain 15–33 billion neurons, each connected by synapses to several thousand other neurons. These neurons communicate with one another by means of long protoplasmic fibers called axons, which carry trains of signal pulses called action potentials to distant parts of the brain or body targeting specific recipient cells.
[A]:
nerve