Gestalt theory is based on the idea that

A) the whole is different from the sum of its parts.
B) the environment affects behavior.
C) social situations influence behavior.
D) science should be used to understand therapy.

Gestalt theory emphasizes that the whole of anything is greater than its parts, suggesting that the whole has a reality of its own, independent from the parts. This principle is fundamental in understanding perception as it suggests that we perceive objects as complete forms rather than a collection of separate parts.