Let's start by going through the second paragraph as a whole. The final sentence of the second paragraph tells us that "a cannibal tadpole is less likely to avoid eating kin when it becomes very hungry, apparently putting its own unique genetic makeup ahead of its siblings'."
The second paragraph begins by telling us that the inclusive fitness theory has been applied in the context of intra-species cannibalism.
What is the inclusive fitness theory? The first paragraph tells us that this theory is based on the realization that genetic attributes are transmitted through generations through both offspring and close relatives. This theory is offered as one possible explanation for why kin recognition exists in the plant and animal kingdoms.
Back in the second paragraph, we learn that spadefoot toad tadpoles eat non-siblings, but release their siblings from their jaws unharmed. However, this is complicated by the final sentence of the second paragraph which tells us that hunger can cause these tadpoles to eat their own siblings.
In this way, spadefoot toad tadpoles' behaviour largely does support kin recognition (as articulated by answer choice (C)), but the final sentence introduces us to behaviour which is inconsistent with kin recognition, "further complicat[ing] the set of facts to be explained by any theory of natural selection that accounts for kin recognition." This is restated by answer choice (A), making it our correct answer.
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