What was the purpose of project mercury?
a.
to land on and explore the moon
b.
to orbit, rendezvous, and dock spacecraft
c.
to see if a man could survive in outer space and reenter the earth's atmosphere
d.
to test the effects of prolonged spaceflight on the human body

The goal was to orbit a spacecraft around the Earth. It has people in it. So the answer is B.

Defintion of variation: a different or distinct form or version of something.
mathematic definition: a change in the value of a function due to small changes in the values of its argument or arguments.
i would say that it is D how different a data set is