Which of the following, if true, would be most likely to make it difficult to verify the collision hypothesis in the manner suggested by the author? A. The Moon's core and mantle rock are almost inactive geologically. B. The mantle rock of the Earth has changed in composition since the formation of the Moon, while the mantle rock of the Moon has remained chemically inert. C. Much of the Earth's iron fell to the Earth's core long before the formation of the Moon, after which the Earth's mantle rock remained unchanged. D. Certain of the Earth's elements, such as platinum, gold, and iridium, followed iron to the Earth's core. E. The mantle rock of the Moon contains elements such as platinum, gold, and iridium.