We can learn about the living conditions of a vanished

Thoughts on the prompt:
It says that language reveals how its speakers lived. Then a conclusion is drawn based on the presence of three words and the absence of a word for "sea."

Thoughts on the answer choices:
A: Fish can come from lakes and rivers. If you fail to consider this, you might think this choice weakens the argument. It's a trap!
B: This is noteworthy. This could mean speakers of Proto-Indo-European actually did live near a sea. Good answer choice.
C: This is irrelevant.
D: This is irrelevant.
E: This is irrelevant.

I would choose answer choice B.

Side note: Languages vary in the number of names they have for colors. The minimum number of terms for any known language is two (light and dark). But this doesn't mean that speakers of that language don't see colors the way English speakers do. There's a lot of interesting stuff about color-naming on Wikipedia.