According to the Punnett Square shown above A.
there is a 50% probability that an offspring will have brown eyes and a 50% probability that an offspring will have blue eyes.

B.
there is a 75% probability that an offspring will have blue eyes and a 25% probability that an offspring will have brown eyes.

C.
there is a 75% probability that an offspring will have brown eyes and a 25% probability that an offspring will have blue eyes.

D.
there is a 100% probability that an offspring will have one brown eye and one blue eye.

C. There is a 75% probability that an offspring will have brown eyes and a 25% probability that an offspring will have blue eyes.

Explanation:

Note that the brown eyes is the dominant trait, denoted by B, while blue eyes is the recessive trait, denoted by b. In all cases of the Punnett square, if there is a dominant and recessive trait, the dominant trait will always come out on top.

The given Punnett square:

Note that there are 3 options (BB, Bb, Bb) respectively, in which there is the dominant trait B (brown eyes). Only in one case is there only the recessive trait b (blue eyes), or a 1/4 chance of obtaining blue eyes. Therefore, there is a 3/4 chance of obtaining a brown eye:

C. There is a 75% probability that an offspring will have brown eyes and a 25% probability that an offspring will have blue eyes.