Which question is scientifically testable allowing a conclusion to be made based on scientific evidence?

A) Is red better than blue?
B) Is the school day is too long?
C) Is gold heavier than silver?
D) Is summer better than winter?

the correct answer is: b. pantala flavescens, because these organisms would have a high level of genetic variation due to sexual reproduction.  

because involves two organisms (parents) whose genetic material combines, sexual reproduction leads to genetic variation in new generations of offspring. the offspring is an unique organism, with new genome, more protected with the higher ability to adapted. this process is fundamental to evolution.

i think the answer is a.keratin is the pigment responsible for skin color.