Use the terms "atom" and "element" to explain what makes silver and gold different.

just finished the test, the answer is d, greg is the least cost-effective because he charges the most for the project

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.