Pretty sure he used female gametes
Answer: I would go with B. Here’s why: An index fossil is usually easily recognizable, and underwent a wide geographic distribution. What leads me to believe B is the correct answer, is because it’s something that existed “ all over the world”.
Unlike other ways of reproduction, sexual reproduction provides variation through inheriting various genes. This variation is essential for adaptation as it would not just create a copy of the original life form, but rather a different unique life form that could adapt to something, and then have it's own offspring with the adapted trait.
I believe it's lactic acid and energy.
The awnser would be D the tilt on the earth on its axis