Question

Dr. difonzo notices several students nodding in agreement as he lectures. subsequently, his rhetoric becomes more confident and more passionate. the students have provided _____ reinforcement.

Answer 1

i think the students have provided : Positive reinforcement

By nodding during his lectures, Dr. Difonso will get the perception that students pay attention to what he's talking about.
By getting this, Dr. Difonso will fell more valued and validated by his students, and this will lead to more passion for his works.