Because the pandas had already been weakened by disease and drought, a harsh winter would have had______consequences for them.

【正确答案】 C

【答案解析】解析：preventive“预防的，防止的”；regressive“后退的，逆行的，退化的”；catastrophic“灾难的，惨重的”；moderate“有节制的，温和的，适度的，中等的”。由题意可知，此处应含有“惨重的、严重的”之意。故选C。