1. 

A. 1
B. 2
C. 3
D. 4

Answer: Option A

Explanation:

In this series, the figures increase the amount of shading by one-fourth and, once a square is completely shaded, starts over with an unshaded square. In the second segment, you will notice that the figure goes from completely shaded to completely unshaded. This is why choice a is the correct choice.