A Researcher Wants to See If a Protein-Enriched Diet Will

A researcher wants to see if a protein-enriched diet will enhance the maze-running performance of rats.One group of rats is fed the high-protein diet for the duration of the study; the other group continues to receive standard rat food.What types of groups are represented in this study

A)  The high-protein group is an experimental group; the standard food group is a control group. 
B)  Both groups are experimental groups. 
C)  Both groups are control groups. 
D)  The high-protein group is a control group; the standard food group is an experimental group.