[单项选择]

Less than a year ago, a new generation of diet pills seemed to offer the long-sought answer to our chronic weight problems. Hundreds of thousands of pound-conscious Americans had discovered that a drug combination known as "fen-phen" could shut off voracious appetites like magic, and the FDA had just approved a new drug, Redux, that did the same with fewer side effects. Redux would attract hundreds of thousands of new pill poppers within a few months.
But now the diet drug revolution is facing a backlash. Some of the nation’s largest HMOs, including Aetna U.S. Healthcare and Prudential Healthcare, have begun cutting back or eliminating reimbursement for both pills. Diet chains like Jenny Craig and Nutri System are backing away from them too. Several states, meanwhile, have restricted the use of fen-phen. Last week the Florida legislature banned new prescriptions entirely and called on doctors to wean current patients from the drug within 30 days; it also p
A. the problem of obesity that has obsessed the Americans for a long time.
B. the problem that is of great weight and significance.
C. the vital problem caused by the pills.
D. the threatening situation we are facing in the long run.