Which statement best describes what Sendhil Mullainathan calls "behavioral hazard"?

A. Insured individuals consistently use too much healthcare because they pay less than the full price

B. Research has shown that copays often cause people not to use highly effective drugs

C. Some individuals choose not to buy insurance, but regret that decision later when illness strikes

D. Insured individuals have less incentive to live healthily, knowing that their healthcare costs are largely covered