What is the primary key? a. a table that doesn't relate to any other tables b. the one field in the table that contains only unique entries c. the duplicate field in a table that crosses multiple tables d. an object providing determining data on the properties for each field

Only B is true, but it suggests there is only one such field in a table. You can mark multiple fields as unique. A primary key is intended to uniquely identify a table record (e.g., from other tables) and in order to do that, it has to be unique (ie., this is a consequence of it being a primary key).

these  signals travel  down a part of the neuron called the axon, which is like a wire that carries the  signal  to othernerve  cells. on average a  nerve  cell sends a  signal  at about 50 meters per second, which is over 100  miles  an hour!

why wouldnt you just google the words bud? not that hard to