[单项选择]

Disability among the elderly has declined markedly in the United States in the past two decades. In 1984, 25 percent of the elderly population reported difficulty with activities associated with independent living. By 1999, the share had fallen to 20 percent, a decline of one-fifth. Although these basic facts are well known, their interpretation is not clear. Is the reduction in disability a result of improved medical care, individual behavioral changes, environmental modifications that allow the elderly to better function by themselves, or other demographic changes Will the trend continue, or is it time limited What does the reduction in disability mean for years of healthy life and labor force participation
The researchers David Cutler, Mary Beth Landrum, and Kate Stewart focus on disability caused by cardiovascular disease to investigate the role of improved medical care on reductions in disability. By looking at just one condition, they can analyze health shocks and t
A. the effect of disability reductions is still unclear
B. treatment costs of the non-disabled are higher than those of the disabled
C. the initial treatment costs of acute cardiovascular disease are too much
D. medical costs for a more healthy population are lower