Question

The seasons are caused by
a. Earth’s varying distance from the sun.
b. Earth’s changing rate of rotation.
c. the tilt of Earth’s axis as Earth revolves around the sun.
d. shifting climates on Earth’s surface.

Answer 1

It is C because when the poles point away form the sun in is winter 

Answer 2

a). Earth’s varying distance from the sun ...
     has no noticeable effect on climate throughout the year.
    (The effect can be measured with very sensitive instruments
     and great data-crunching machines.)

b. Earth’s changing rate of rotation ...
    has no noticeable effect on anything. 
   (The effect on the length of the day can be measured with
    very sensitive instruments.)

c. the tilt of Earth’s axis as Earth revolves around the sun ...
    This is the cause of our seasons on Earth.

d. shifting climates on Earth’s surface ...
    This is only noticeable over a period of hundreds of years. 
    There are still many people who don't accept that it's real. 
     It has nothing to do with the seasons.