In between classes Marla usually sits around working on Sudoku puzzles. This is an example of __________

A) homeostasis.
B) drives.
C) stimulus motives.
D) curiosity.

Stimulus motives refer to engaging in behaviors that are not necessary to fulfill basic biological needs but are driven by the desire for stimulation or novelty. Marla working on Sudoku puzzles between classes is an example of a stimulus motive because it is not necessary for her survival or well-being but provides mental stimulation and entertainment.