Why do stars appear to move across the sky

The stars themselves are not moving.

The reason stars "move" is because we are orbiting around the Sun, and the Earth is rotating.

From our perspective they seem to be moving, but they are not.

Hope this helps!

this allows people to make the best decision or pursue the best option. when alternatives are weighed using their advantages and disadvantages, the option whose disadvantages outweigh the advantages (based on a qualitative or quantitative analysis) are shunned while those whose advantages outweigh their disadvantages are pursued.  

the answer would be c. motion and direction

i hope this : )