It Appears That Eukaryotic Diversity Took Off Around 800 Million

It appears that eukaryotic diversity took off around 800 million years ago. Which of the following is thought to be responsible for this?

A) By 800 million years ago, enough time had passed since the arrival of eukaryotes for evolutionary adaptation to take place.
B) Eukaryotic organisms first arrived 800 million years ago, so when they did, they quickly diversified.
C) Chloroplasts first arrived 800 million years ago.
D) The ability to prey on other protists originated or expanded 800 million years ago, setting in place an evolutionary arms race.
E) All of these choices are correct.