How does exercise contribute to environmental health?

When the majority of people start to cycle, then cleaner air can become a reality. Increased fitness also leads to the support for local farms. 

so we know the answer cannot be c because no insect or animal starts as an adult

the answer is a. a swimming larvae

because since they are sea animals they automatticaly have to know how to swim they cannot just sink to the bottom

sorry if this is the incorrect answer.