Chan drinks four cups of coffee each day. One day, Chan skips the two cups he usually has in the morning, and he gets a terrible headache and finds he cannot concentrate. MOST specifically, Chan may be experiencing ______.

________ is to aggression as ________ is to cooperation

a. Cognitive dissonance; empathy b. Dehumanization; empathy c. Rewards; punishment d. Self-justification; self-affirmation

Participants in psychological research are free to end their participation at any time, with no threat of retribution or punishment. This freedom is consistent with which feature of ethical research?

A) external validity B) beneficence C) being just D) respecting people