An aquaculture facility hatched salmon eggs and released young fish into a river leading to the ocean. The fish fed and grew in the ocean, and in a few years they returned to the facility. Because the number of returning fish was low, a scientist suggested adding a chemical to the river that would __________.

• A. allow them to form a cognitive map
• B. increase their capacity for spatial learning
• C. provide an opportunity for associative learning
• D. enhance social learning
• E. enable them to imprint on the facility