Question

proposition that dreams represent the brains attempt to understand electrical activity during rem sleep
activation - synthesis supposition
activation - synthesis speciation
activation - synthesis hypothesis
activation - synthesis causation
activation - synthesis abiogenesis

Explanation:

The activation - synthesis hypothesis proposes that dreams are the brain's interpretation of electrical activity during REM sleep. "Supposition" is too general; "speciation" refers to species formation; "causation" is about cause - effect in a general sense; "abiogenesis" is about the origin of life. The correct term for this scientific idea is "hypothesis".

Answer:

activation - synthesis hypothesis