The insect body plan includes many groups of serially repeated units. for example, there are typically three pairs of legs, one on each of the three segments of the thorax. which option best describes how these pairs of legs develop and evolve?

Does Natural selection or evolution involve with this? it sounds like spiders and other Insects or bugs that have evolved to be able to have limbs in order to survive in a environments that would require extra limbs. probably from genes being passed on and also being mutated positively in order for the newer species to better adapt. the pair of legs could have been increased because of the environment that requires it and also as the mating changes it's basically survival of the fittest.