over time a particular plant has developed a larger stem. Which of the following is a possible advantage of having longer stamen?

A) a longer stem could ensure that an insect brushes against another and picks up pollen****
B) a longer stem could ensure that the flower produces more nector
C) a longer stem could ensure that pollen could reach the ovary and fertilize the egg
D) a longer stem could ensure that the developing flower is well protected

I agree but the phasing is strange. More likely the insect lands on the longer one.