Assuming that in and rt are fixed values and that rl is variable, select the correct argumentation that shows that maximum power is delivered for rl=rt. assuming that and are fixed values and that is variable, select the correct argumentation that shows that maximum power is delivered for . taking the derivative and setting it equal to zero, we have dpldrl=0=(in)2(rt)2(rt+rl)−2(rl)2rt (rt+rl)3, which yields rl=rt. taking the derivative and setting it equal to zero, we have dpldrl=0=(in)2(rt)2(rt+rl)−2(rt)2rl (rt+rl)3, which yields rl=rt. taking the derivative and setting it equal to zero, we have dpldrl=0=(in)2(rt)2rl−2(rt)2(rt+rl) (rt+rl)3, which yields rl=rt. taking the derivative and setting it equal to zero, we have dpldrl=0=(in)2(rl)2rt−2(rt)2(rt+rl) (rt+rl)3, which yields rl=rt.