The population of songbirds throughout England has decreased in recent years. Many people explain this decrease as the result of an increase during the same period in the population of magpies, which eat the eggs and chicks of songbirds. Which one of the following, if true, argues most strongly against the explanation reported in the passage?
A: The number of eggs laid yearly by a female songbird varies widely according to the songbird's species.
B: Although magpies eat the eggs and chicks of songbirds, magpies' diets consist of a wide variety of other foods as well.
C: The population of magpies has increased because farmers no longer shoot or trap magpies to any great extent, though farmers still consider magpies to be pests.
D: Although the overall population of magpies has increased, in most areas of England in which the songbird population has decreased, the number of magpies has remained stable.
Choose A, B, C or D as your solution.
D