Two species of marine mammals have become extinct in modern times: the atlantic gray whale and the steller sea cow both joined the extinct species list back in the 1800's. more recently, scientists have declared the caribbean monk seal to be extinct. the best explanation for the extinction of these three species is a) deforestation. b) global warming. c) over-hunting by man. d) a drop in sea level.

The answer is C)over-hunting by man. This is the best answer through elimination of the remaining answers. A)deforestation is not true as deforestation would have limited effects on large marine mammals. B) global warming is not true as two species were extinct in the 1800s, where the effects of global warming would not have yet been visible. D)a drop in sea level is not true as the sea level has actually been rising in recent centuries due to global warming. In contrast, it is known that harvesting of whales in the 1700s and 1800s was responsible for a dramatic drop in whale populations, and we can assume that hunting was also responsible for the decimation of steller sea cow and Caribbean monk seal populations.