Which Is the Best Characterization (Description) of Operant Conditioning

Which is the best characterization (description) of operant conditioning?

A) A person performs some action, and depending on what happens as a consequence of that action, the likelihood of that same behavior occurring again
Will either increase or decrease.
B) Automatic responses become associated with new stimuli when they occur at the same time.
C) Over time and with repeated experience, the person changes how to best understand a concept or problem.
D) The person is exposed to a great deal of information, the person relates the new information to preexisting knowledge, and then organizes all the new information in a coherent way.