GMAT Critical Reasoning (CR) | Re: Lyme disease is caused by a bacterium transmitted to humans by deer ti

This is the hardest CR question I've seen on the GMAT so far. I only understood it after drawing a diagram for myself to visualize the populations of ticks, mice, and non-infected animals. B is correct because the NUMBER of ticks that are getting infected can only decline if the population of ticks after the increase of non-infected animals remains constant. But the phrasing of B is very difficult to decode.

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