Which global wind belt do we live in?

Okay, first of all, I don't know what "do we live in" means. I am guessing you're talking about the United States.

We live in the Prevailing Westerlies, which blow in the middle latitudes. Most of North America fits into this belt.

C 10% Condition.

Step-by-step explanation:

Let's Look at them one by one.

A: Large Enough sample condition.

this is met because 600 students is a good number to carry out a surwey.

B: Randomization,  600 incoming freshman are definitely random.

C: we are left with C so the answer is C.