After taking a particular drug, Hal began feeling that time was passing very slowly, and he began having profound thoughts about the nature of time and the universe. While this first experience was at first deeply moving, leading to feelings of elation, the next time Hal tried this drug, he felt anxious and depressed. What drug did Hal probably take?a) marijuanab) ecstasyc) heroind) cocaine

Yes it does it plays a big role

Immunization is the introduction of a foreign substance to provoke  the immune response system.  immunizations are the same as vaccinations. it introduces foreign (but dead/ weakened) illnesses to train the body to fight against them. specific viruses and bacteria have specific antigens, antigens act sort of like name tags. these name tags the immune system recognize what's dangerous to the body and what's safe. 

Wouldnt the answer be b?