Can you explain to me how this is the answer, please and thank you!

(5) A nutritionist wants to know the mean weight of a 10 year old. He will collect a random sample, and construct a 95% confidence interval for the mean weight. The Margin of Error should be no more than 1 pound. Suppose the standard deviation for the weight of a 10 year is believed to be in the interval [5, 10]. What is the minimum sample size required to ensure the margin of error is no more than 1 pound? (A) 385 (B) 262 (C) 96 (D) 4 (E) 484