A. Natural Selection. This is because the weeds that are not resistant to it die out before they can reproduce, but the resistant ones grow to maturity and then reproduce, passing down the resistance gene. Over time, the resistance gene would become a normal thing in weeds, while the non-resistant gene would not exist anyone, since the gene could not be passed on.
B. A moray eel eats a fish swimming by. Predators are organisms that eat other organisms. If this helps, thank me. If this really helps, thank me and, crown me brainliest answer. Also, rate, and comment. This helps me to improve answering, and helps you to get a better answer.