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.