My guess would be A.
It’s excepted by the scientific community that climate change is a thing, and that we human are the cause.
We know this, because of the type of carbon that in the air is the same type as those found in fossil fuels.
So, because carbon dioxide is a greenhouse gas, one of the predictions is that as we add more carbon dioxide in the atmosphere the earth gets warmer, and the polar icecaps start to melt and that adds to the volume of the sea water.
So, it’s A.
I hope that helps.