correct answer is C. 3200
We are given that our population is 32,000 people. The sample size of the population must be less than or equal to the population, so let's go through the options:
A. A sample of 3,200,000 people: This cannot be possible because the population is only 32,000.
B. A sample of 32,000,000 people: Again, this exceeds our given population size of 32,000.
C. A sample of 3,200 people: This is less than the population size of 32,000, so it is possible for the sample size to be this number.
D. A sample of 320,000 people: This number is larger than the population size.
Therefore, after checking each option, we find that option C is the only possible sample size. It is the only number that is less than the population size of 32,000.
So, the correct answer is C. 3200.