<span>In any population of bears, some individuals have thick fur, some have thin fur, and some are in between. As temperatures increase with the passage of time, the survival of bears with thin fur will increase, and the number of bears in the population with thick fur will decrease.</span>
RNA is similar to DNA. In RNA, uracil replaces the thymine. So, the base that is replaced is called the thymine.
A couple limitations could be human variability meaning each human is a little bit different from the last. there could be a lot of other factors impacting your outcome.
Also, the risk of losing a life. For example it is more risky to conduct a research on if saturated fats give you cardiovascular disease on humans then it would be to conduct this research on rats.
The answer is B. We don't always have exact proof but our observations tell us more than we already know.
A: an ecosystems organisms become larger as succession
