Placing a Harmless, Odorless Mark to Some Area of the Face

Multiple Choice

Placing a harmless, odorless mark to some area of the face, and placing food behind a barrier so that only one of two animals can see it are techniques that have been devised to measure an animal's ability in

A) number sense and abstract concepts.
B) insight learning.
C) self-recognition and perspective taking.
D) social learning.