Answer: Option B
Step-by-step explanation:
There was rise in the population of bed bug during the mid twentieth century and there was no control on them.
The use of pesticide was the one and only solution on the pests. DDT was a very effective pesticide that killed bed bugs.
DDT was banned after sometime because it entered the food chain and its level was increasing significantly at each level.
But before that it was very effective in eradicating bed bugs.