In an Experiment Designed to Test Memory Processes, One Group

In an experiment designed to test memory processes, one group was given special instructions and asked to group the items on a list into categories while trying to memorize them. A second group of participants was given the same list, but did not receive any special instructions. In this study, which group is the experimental group?

A) the group that received the special instructions
B) the group in which the participants remember the most items from the list
C) the group that did not receive any special instructions
D) the group in which the participants remember the fewest items from the list