Explanation
Correct answer: B.
Choice B is the best answer. If there are parasites that feed on both snakes and frogs, they could carry BovB from snakes to frogs. HT could occur “indirectly” through those encounters, which frogs are more likely to survive than snake encounters.
Why the other choices are wrong
Choice A
Choice A is incorrect. The team’s conclusion specifically argues that BovB is transmitted from snakes to frogs via HT, and this choice doesn’t mention snakes.
Choice C
Choice C is incorrect. The team argues that BovB is transmitted from snakes to frogs via HT, and this answer choice discusses a scenario in which the gene is not transmitted.
Choice D
Choice D is incorrect. Whether or not frog species with BovB are advantaged isn’t relevant to the team’s conclusion about how the gene is transmitted.