The correct answer is (a), (b) and (c) only. Explanation & Key Takeaways: • The insecticide is any toxic substance that is used to kill insects. • It is the substances that are used primarily to control pests that infest cultivated plants or to eliminate disease-carrying insects in specific areas. • Using insecticides safely depends on many things. Some of the most important factors include selecting the appropriate product and using that product according to the label directions. The label directions are written to minimize the risk of problems and to define the legal uses for the product. • Following things must be considered important while using insecticides- • Choice of insecticide’s type- Depending upon the constituent of insecticide the choice of insecticide must be done in order to minimise the harmful effects. • The efficiency of insecticides- Depending upon the efficiency of insecticides they must be selected so that it works efficiently. • Dose of insecticides - the dose must be in a minimum amount so that it works efficiently without causing a harmful effect to humans. • Hence, (a), (b) and (c) are correct.