According to paragraph 6, which of the following explains the fact that a well-fed nestling does not beg loudly for more food? A. There is no benefit for a nestling to get more food than it needs to survive. B. By begging loudly for food it does not need, a nestling would unnecessarily expose itself to danger from predators. C. If a nestling begs loudly when it is not truly hungry, then when it is truly hungry its own begging may be drowned out by that of its well-fed siblings. D. More of a nestling's genes will be passed to the next generation if its hungry siblings get enough food to survive.