Fred's Correspondence College wants to construct a 90% confidence interval for the mean starting salaries of its graduates. A sample of 100 recent graduates has a mean of $50,000 and a standard deviation of $30,000. Assuming the population of graduates' starting salaries is normally distributed, the College's confidence interval is closest to: A) $0 to $100,000. B) $45,000 to $55,000. C) $44,000 to $56,000.