Can someone please help me to understand this? A simple random sample of 1200 adult Americans is selected, and each person is asked the following question. "In light of the huge national deficit, should the government at this time spend additional money to establish a national system of health insurance?" Only 39% of those responding answered "yes."

This survey
A) is reasonably accurate since it used a large, simple random sample.
B) probably overstates the percentage of people that favor a system of national health
insurance.
C) probably understates the percentage of people that favor a system of national health
insurance.
D) is very inaccurate, but neither understates nor overstates the percentage of people
that favor a system of national health insurance. Since simple random sampling
was used, it is unbiased.

I know the answer is "C" but I genuinely don't understand why it is. If someone could explain it'd be much appreciated, thanks.

Determine if the following statement is true or false. the normal curve is symmetric about its​ mean, mu. choose the best answer below. a. the statement is false. the normal curve is not symmetric about its​ mean, because the mean is the balancing point of the graph of the distribution. the median is the point where​ 50% of the area under the distribution is to the left and​ 50% to the right.​ therefore, the normal curve could only be symmetric about its​ median, not about its mean. b. the statement is true. the normal curve is a symmetric distribution with one​ peak, which means the​ mean, median, and mode are all equal.​ therefore, the normal curve is symmetric about the​ mean, mu. c. the statement is false. the mean is the balancing point for the graph of a​ distribution, and​ therefore, it is impossible for any distribution to be symmetric about the mean. d. the statement is true. the mean is the balancing point for the graph of a​ distribution, and​ therefore, all distributions are symmetric about the mean.