Correct Answer: (B) Mental Relaxation

Step 1 - Identify her problem:

Shweta's difficulty is psychological. She is over-stressed and anxious because of examination pressure.

Step 2 - How exercise helps here:

Physical activity releases endorphins, often called feel-good hormones. It reduces the level of stress hormones, improves sleep and concentration, and gives the mind a break from study. This is mental relaxation.

Step 3 - Why the others are wrong:

Building strength, socialising and reducing disease risk are all genuine benefits of exercise, but none of them addresses the problem stated in the question.

Hence, option (B) is correct.