Which of the following most logically completes the reasoning?
When species are extensively hunted, individuals that reach reproductive maturity early make up a larger proportion of the population, because they have a better chance of reproducing. When species face diminished food resources, on the other hand, individuals tend to take longer to reach reproductive maturity. These considerations may help settle whether the primary cause of the gradual disappearance of North America's mastodons, prehistoric animals related to elephants, was diminished food resources or human hunting, since __________.
把它還原一下, SINCE (B) the average age at which mastodons reached reproductive maturity can be established from mastodon tusks, of which there are many fossils dating from different periods, these considerations may help settle whether the primary cause of the gradual disappearance of North America's mastodons, prehistoric animals related to elephants, was diminished food resources or human hunting,