Which chamber receives blood from all the body veins

Do you know if there is just 1 answer? I think it is both the left atrium and right atrium.

If just 1 answer, try right atrium

allowed for the prediction of the properties of missing elements.

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.