问题：
[单选题]It’s not known whether chronic stress will harm the narwhals, but researchers are concerned. “The results are disturbing because they suggest narwhals aren’t physiologically equipped to sustain, in good health, repeated exposure to stressful events,” says Randall Reeves, a marine mammal expert in Hudson, Canada, who chairs the International Union for Conservation of Nature Species Survival Commission’s Cetacean Specialist Group. “It makes me worry that narwhals are even more specialized than was previously thought, and that they are thus less resilient to rapid environmental change.” (Para. 7) What concerns the researchers is:
AChronic stress will kill the narwhals.
BNarwhals can’t handle the stressful events physically.
CNarwhals are too specialized as marine mammals.
DNarwhals are resilient to rapid environmental change.
