______ is one of the primary laws of learning.

Edward Thorndike's theory of connectionism (trial-and-error learning) identifies three PRIMARY (foundational) laws of learning — the Law of Readiness, the Law of Exercise, and the Law of Effect — that together explain how a stimulus-response (S-R) bond is formed and strengthened or weakened.

Beyond these three, Thorndike also proposed several SUBORDINATE (secondary) laws that refine specific learning situations — such as the law of multiple response, the law of set/attitude, the law of prepotency of elements, the law of response by analogy, and the law of associative shifting — but these are not counted among the three primary laws.

Applying this to the given options: only 'Law of effect' names one of the three primary laws — it states that a response followed by a satisfying consequence is strengthened ('stamped in'), while a response followed by an annoying consequence is weakened ('stamped out'). The remaining three options name subordinate laws Thorndike added later, not primary ones.

• Law of attitude (law of set): a subordinate law describing how a learner's mental/postural readiness or attitude shapes which response is given in a situation.

• Law of response by analogy: a subordinate law describing how a learner transfers a previously learned response to a new but similar situation.

• Law of associative shifting: a subordinate law describing how a response already tied to one stimulus can gradually be shifted to an entirely new, different stimulus through repeated pairing.

Cross-check: each of these three is explicitly classified in Thorndike's own writings as a subordinate/secondary law, confirming that only the Law of Effect, among the given options, is one of the primary laws of learning.