Final answer:
Flies typically reproduce by laying eggs in decaying matter, which then hatch into larvae that feed on the organic material. Each life stage of a fly, from egg to adult, looks different.
Step-by-step explanation:
Flies reproduce by laying eggs, specifically through option A: Through eggs laid in decaying matter. They seek out decaying organic material, such as dead animals, onto which they deposit their eggs. The hatched maggots then feed on this decaying flesh. This process can even be used by forensic entomologists to determine the time of death based on the stages and types of maggots found.
Insects such as flies undergo a life cycle that includes the stages of egg, larva (maggot), pupa, and adult, and each stage looks distinct from the others. While warm weather conditions can spur flies to focus on reproduction, their offspring start as eggs, contrasting with some rare exceptions like the deer ked, which gives live birth to larvae.