B. F. Skinner trained a rat to sit up, then to sit and raise an arm, then to wait for music before sitting up, and so forth, until it responded to the "Star Spangled Banner" by raising the flag and saluting. What procedures were necessary?

(a)classical conditioning and operant conditioning

(b)shaping and chaining

(c)assimilation and accommodation

(d)positive reinforcement and negative reinforcement