Which of the following is not dissociative? a. pcp b. mescaline c. ketamine d. dextromethorphan

B. Mescaline

Mescaline is not a dissociative drug but a psychedelic alkaloid of phenethylamine class that has hallucinogenic effects. 

Meanwhile, phencyclidine (PCP), ketamine and dextromethorphan at high doses is classified as dissociative general anesthetic that distort perceptions of sight and sound and produce feelings of detachment from the environment and self. Other effects include analgesia, hallucinations, mania and amnesia.

so we know the answer cannot be c because no insect or animal starts as an adult

the answer is a. a swimming larvae

because since they are sea animals they automatticaly have to know how to swim they cannot just sink to the bottom

sorry if this is the incorrect answer.