Natural selection can cause less desirable traits to a. appear in a population b. disappear in a population c. arise in a population d. become more common in a population

Think of Natural selection like this. If the earth becomes hotter and only some humans can survive the heat because of a trait they have then humans who have that trait would want to reproduce with people who also have that trait right? So why would they want to have a kid with someone who doesn't have that trait right. Their kid could die. So since no one is going to want to reproduce with the people who have the less desirable trait, they will just die without having given their trait to an offspring. So if they die, what also dies? The trait meaning it will disappear from the population. 

Both prokaryotic and eukaryotic cells have ribosomes and cell membranes