A health organization wants to estimate the average cholesterol level of adults in a city. They require $99\%$ confidence that the sample mean is within $4$ milligrams per deciliter of the population mean. Prior data indicates that the population standard deviation is $22.5$ milligrams per deciliter. What is the minimum sample size that is needed? Would sampling only from one clinic be appropriate?

• A. $110$, Sampling only from one clinic is not appropriate.
• B. $110$, Sampling only from one clinic is appropriate.
• C. $210$, Sampling only from one clinic is appropriate.
• D. $210$, Sampling only from one clinic is not appropriate.

Answer: (D)