In this question, I selected option B only since C only works if we assume that the situation of guppies being well/less fed is more likely than tadpoles being anesthetized. The correct answer is B and C. I understand why B is correct.
For C - How do we know that being anesthetized is not a common occurrence for tadpoles? Perhaps some plants in tadpole habitats often secrete anesthetic. The passage presents no such evidence. They are basically asking us to guess/know this. I know “common sense” suggests this but isn’t that one of ETS’s common tricks - to trick you into making assumptions that are not stated?
Thank you!