A researcher would like to estimate the true mean daily water intake for all Canadians. She measures the daily water intake (in ml) for a sample of Canadians and calculates a 95% confidence interval for to be (1771.6, 1928.4). Daily water intake for Canadians is known to follow a normal distribution with standard deviation 280 ml. What sample size did the researcher take? (A) 16 (B) 25 (C) 36 (D) 49 (E) 64