Based on the Results of Experiments Raising Flies at Higher

Based on the results of experiments raising flies at higher levels of oxygen, which of the following statements is most probable?

A) Mutations that increase body size cannot occur.
B) Mutations that increase body size are more likely to be selectively advantageous at high levels of oxygen than at current levels of oxygen.
C) Mutations that increase body size are less likely to be selectively advantageous at high levels of oxygen than at current levels of oxygen.
D) Mutations that decrease body size are more likely to be selectively advantageous at high levels of oxygen than at current levels of oxygen.
E) Body size is not a heritable trait.