Final answer:
An IGR inhibits a cockroach's growth and reproductive abilities as part of a biological control strategy, which helps manage insect populations and resistance, and is generally safer and cost-effective.
Step-by-step explanation:
A good reason to use an Insect Growth Regulator (IGR) during a cockroach treatment is because it inhibits a cockroach's ability to move on to the next stage of their life cycle (Option A) and it inhibits a cockroach's ability to reproduce (Option B). IGRs are a form of biological control that targets the growth stages of insects, preventing them from reaching maturity and, consequently, reducing future populations.
This approach helps in controlling insect populations and can contribute to insect resistance management. It is also a method that is generally safer for the environment, as it aims to protect surroundings and lower costs associated with pest control. While increasing hunger in cockroaches may be a side effect of some pest control strategies (Option C), it is not a primary function of IGRs.