Why Did It Take So Long for Eukaryotes to Evolve

Why did it take so long for eukaryotes to evolve after photosynthetic prokaryotes began releasing O₂ into the atmosphere?

A) O₂ moves slowly through larger cells,making it hard for them to gather O₂;thus,higher O₂ concentrations had to accumulate before eukaryotic cells could be efficiently supported.
B) The ability to use O₂ had to evolve before cells could survive in an O₂-rich atmosphere.
C) The ability to break down the waste products of O₂ use had to evolve before cells could use it to create energy.
D) Enough prokaryotes had to become extinct to provide eukaryotes with a niche to occupy before they could evolve.