Final answer:
Reciprocal determinism is the best explanation for Randy's situation, where his substandard academic performance is both a result and a cause of his feelings of academic inferiority.
Step-by-step explanation:
The student's situation of substandard academic performance being both a result and cause of feelings of academic inferiority best illustrates the concept of reciprocal determinism. Reciprocal determinism is the idea that our behavior, cognitive processes, and situational context all influence and interact with each other. In this case, Randy's academic performance affects his feelings of inferiority, which in turn can impact his motivation and future academic performance.