Steven had been "hooked" for a while before he decided to "go clean." Within 6 to 12 hours, he started to experience excessive yawning, nausea and vomiting, chills, muscle aches, diarrhea, and insomnia. His behavior disrupted his work and social relationships. These symptoms persist for three days. After a week, he felt better. Steven is probably withdrawing from Group of answer choices a) alcohol. b) cocaine. c) heroin. d) LSD.