The correct statement is:
The sample size of 400 will give a better approximation of population proportion, as it is symmetrical and the mean falls close to the middle of the distribution.
This is because larger sample sizes tend to yield more accurate estimates of population parameters, as they typically exhibit less variability and produce a sampling distribution that is closer to the true population proportion—reflecting the Central Limit Theorem. With a larger sample size (like 400), the sampling distribution is expected to be more normal (and therefore symmetrical), resulting in a mean closer to the population proportion.