Abnormally low levels of the neurotransmitter serotonin are associated with:

Abnormally low levels of the neurotransmitter serotonin are associated with depression.  When the brain produces low levels of serotonin, such signals become much more irregular and brief, thus, producing psychiatric disease processes including depression.

Ibelieve the answer is c. both plants and fungi undergo photosynthesishope my answer is to you : )