DDT is a pesticide banned in the United States for its danger to humans and animals In an experiment on the impact of DDT six rats were exposed to DDT poisoning and six rats were not exposed For each rat in the experiment a measurement of nerve sensitivity was recorded The researchers suspected that the mean nerve sensitivity for rats exposed to DDT is greater than that for rats not poisoned The data follow Poisoned rats 12 207 16 869 25 050 22 429 8 456 20 589 Unpoisoned rats 11 074 9 686 12 064 9 351 8 182 6 642 Let be the mean nerve sensitivity for rats poisoned with DDT Let 2 be the mean nerve sensitivity for rats not poisoned with DDT The numerical value of the standard error of the difference in sample means is OA 9 02 OB 4 05 O C 1 30 OD 2 71