Why do elephants not get cancer ?

But elephants are far less prone to cancer than humans are, even though they are much bigger and live very long lives. In 2015, Schiffman found that elephants have 20 copies of a gene called p53, well known for its ability to fix damaged DNA, which can lead to cancer. Humans have only one.

Explanation:

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.