An ecologist is examining whether the number of fish caught in a large river basin has changed since a fire burned some of the surrounding forested area and vegetation along the river. Data in the form of fishing reports was available for a five-year period before the fire. From a random sample of 195 fishing reports before the fire, the mean catch was 6.3 fish with a standard deviation of 1.6. In a random sample of 143 reports three years after the fire, the mean catch was 7.1 fish with a standard deviation of 2.1. Which of the following represents the standard error of the difference in the mean number of fish caught before and after the fire? A. √1.6/ 2.1 + 195 /143
B. √2.12 + 143
C. √1.62/ 2.12 + 195 /143 195
D. √1.62/ 2.12 +1195 /1143
E. √1.62 /195 +2.12 /143