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 they tried to memorize them. A second group of participants was given the same list, but they did not receive any special instructions. In this study, the experimental group is ​

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