A researcher is investigating whether a difference exists in the mean weight of green-striped watermelons grown on two different farms: one that uses organic methods and one that uses non-organic methods. The mean and standard deviation of the weights in a random sample of 43 watermelons from the organic farm were 18 pounds and 2 pounds, respectively. The mean and standard deviation of the weights in a random sample of 40 watermelons from the non-organic farm were 20 pounds and 1.7 pounds, respectively. Which of the following represents the standard error of the difference in the mean weights of watermelons from the two farms? a. 2+1.7b. c. d. e.