Final answer:
LSD (Lysergic Acid Diethylamide) became a primary psychedelic drug for those in the counterculture, used to reject traditional social norms and for spiritual or recreational experiences.
Step-by-step explanation:
The psychedelic drug that became a rite of passage for many in the counterculture is B) LSD (Lysergic Acid Diethylamide). LSD, which is also known by various other names such as acid, blotter, and microdots, is one of the most potent mood and perception-altering hallucinogenic drugs. It is synthesized from lysergic acid, which is found in a rye fungus, and was commonly used during the 1960s by those seeking to reject traditional social values and achieve greater spiritual insight or simply to experience the recreational 'high' it provides.