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

A bit is a unit of?, Context: USB data is transmitted by toggling the data lines between the J state and the opposite K state. USB encodes data using the NRZI line coding; a 0 bit is transmitted by toggling the data lines from J to K or vice versa, while a 1 bit is transmitted by leaving the data lines as-is. To ensure a minimum density of signal transitions remains in the bitstream, USB uses bit stuffing; an extra 0 bit is inserted into the data stream after any appearance of six consecutive 1 bits. Seven consecutive received 1 bits is always an error. USB 3.0 has introduced additional data transmission encodings.
data

What did the principle of inertia do for general relativity?, Context: The concept of inertia can be further generalized to explain the tendency of objects to continue in many different forms of constant motion, even those that are not strictly constant velocity. The rotational inertia of planet Earth is what fixes the constancy of the length of a day and the length of a year. Albert Einstein extended the principle of inertia further when he explained that reference frames subject to constant acceleration, such as those free-falling toward a gravitating object, were physically equivalent to inertial reference frames. This is why, for example, astronauts experience weightlessness when in free-fall orbit around the Earth, and why Newton's Laws of Motion are more easily discernible in such environments. If an astronaut places an object with mass in mid-air next to himself, it will remain stationary with respect to the astronaut due to its inertia. This is the same thing that would occur if the astronaut and the object were in intergalactic space with no net force of gravity acting on their shared reference frame. This principle of equivalence was one of the foundational underpinnings for the development of the general theory of relativity.
one of the foundational underpinnings

Why might a mixed race native American need to be officially adopted?, Context: The social identity of the children was strongly determined by the tribe's kinship system. Among the matrilineal tribes of the Southeast, the mixed-race children generally were accepted as and identified as Indian, as they gained their social status from their mother's clans and tribes, and often grew up with their mothers and their male relatives. By contrast, among the patrilineal Omaha, for example, the child of a white man and Omaha woman was considered "white"; such mixed-race children and their mothers would be protected, but the children could formally belong to the tribe as members only if adopted by a man.
the child of a white man and Omaha woman was considered "white"