Which of the following pesticides are non-biodegradable?

In an aquatic food chain,if a water body has $0.003 \; ppb$ of $DDT$,its maximum concentration can be observed in:

Catalytic converters are fitted into automobiles to reduce the emission of harmful gases. Catalytic converters change unburnt hydrocarbons into

Which one of the following is the heavy toxic metal present in waste water from industries?

According to the $..........$ norms,the implementation of $.......$ vehicles was enforced across the country from $1^{st}$ April $2017$.

$DDT$ is a