Which of the following is not a factor in the habitability of a planet

Question

A. whether oxygen builds up in the atmosphere
b. whether the planet has plate tectonics
c. whether the planet has a greenhouse effect
d. size of the planet
e. whether the planet has a sufficient atmosphere

Answer 1

I would guess D. All the other options sound like they are important for habitability at least for a life form that we are familiar with such as aerobic respiration, moderate temperature...