How does the coloration of beetles explain darwin's dangerous idea

Not sure what you mean by dangerous. Charles Darwin had a theory on evolution called Natural Selection. This theory of his essentially states that the organisms that adapt best and most successfully to changes in their surroundings are more likely to survive. A coloration change in beetles would explain this because the color change may help them blend in with their surroundings better, thus escaping predators and having a greater chance of survival. These beetles, due to their success, will become prevalent, meaning that the other beetles will phase out because they have not adapted well to the environment.

the answer is 100% density i've answered this question before and done the quiz myself.

it should be d) transitional fossils.

they show the gradualism of evolution throughout a period of time