I think global warming I'm not sure
The baby boom is also called Post-World War II baby boom, and this already reveals the cause: after the war the economy was raising again, after hard times, and people were optimistic about the future
Answer:
the answer is third one ..............
The counterclaim that best strengthens your argument is :
A counterclaim that presents a popular and reasonable opposing perspective
This will make your counterclaim became easier to accept and appear more reliable
hope this helps