单选题 Which of the following best expresses the main idea of ale passage?

A、 Research has suggested that the neurotransmitter serotonin is responsible for the effects of hallucinogenic drugs on the brain ant on behavior.
B、 Researchers have spent an inadequate amount of time developing theories concerning the way in which the effects of hallucinogenic drags occur.
C、 Research results strongly suggest that hallucinogenic drugs create their effects by acting on the serotonin receptor sites located on target neurons in the brain.
D、 Researchers have recently made valuable discoveries concerning the effects of depleting the amount of serotonin in the brain.

【正确答案】 A

【答案解析】通读全文可以发现，研究者们一直致力于研究the effects of hallucinogenic drugs on the brain ant on behavior与serotonin的关系，并提出了一些设想和建议，故选A。