RC Multiple choice question confusion


Could someone review at my process please?
A) is wrong because we don’t have evidence about Guppies being active we just know that they are alert. So, i cancelled A.
B) We do have evidence about Guppy being the alert ones but we don’t have evidence about tadpoles being less alert. So, i cancelled B.
But for answer choice B it says its correct. Isn’t inferring anesthetized tadpoles as less alert a little outside knowledge? I mean the passage does tell that decrease in activity=less active ones but it doesn’t necessarily say less alert ones.
So, that leaves me to only C.

Could you help me with option choice B please? Isn’t saying partially anesthetized= less alert outside knowledge?
Is B also outside knowledge or not?

Common sense is not outside knowledge.