Answer:
It's definitely C.
Explanation:
Reformulate and break the sentence like this first,
- [The campers who have taken lessons] [were safer during the pool time.]
- First phrase: replace the 'who' by ','
It sounds better !
2. Second phrase: the "[were safer during the pool time.]" is added to complete the first sentence.
When we join to sentences to form one, we usually use conjunctions/connectives and punctuations as well !
So add the ',' to join these two sentences.
The final anwer would be: "The campers, having taken lessons, were safer during the pool time."
I hope that this was helpful enough ! :)
