求助一道PREP逻辑题！！！！！

aglair萱

Lyme disease is caused by a bacterium transmitted to human by deer ticks. Generally, deer ticks pick up the bacterium while in the larval stage by feeding on infected white-footed mice. However, certain other species on which the larvae feed do not harbor the bacterium. If the population of these other species were increased, more of the larvae would be feeding on uninfected hosts, so the number of ticks acquiring the bacterium would likely decline.
Which of the following is most important to ascertain in evaluating the argument?

B whether the size of the deer tick population is currently limited by the availability of animals for tick's larval stage to feed on.

D whether deer ticks that were not infected as larvae can become infected as adults by feeding on deer which infected deer tick's have fed.

我基本上就在B,D当中纠结着！！！就高人指点迷津！！！