Question

in 1939, the use of ddt (a powerful synthetic chemical) as an insecticide was discovered. the united states adopted its widespread use, producing up to 100 million kilograms per year (200 million pounds per year). twenty years later, severe side effects started to be reported as a result of ddt use. which was an advantage of using ddt? insect and pest populations decreased birth defect rates increased cancer rates increased fertility rates decreased

Explanation:

The question asks for an advantage of using DDT. DDT was used as an insecticide. Insecticides are meant to control insect and pest populations. The other options (birth defect rates increased, cancer rates increased, fertility rates decreased) are negative side - effects, not advantages.

Answer:

insect and pest populations decreased