I forgot to mention that lumpers would disagree heavily with what I said above because they believe each species is its own individual species, there is no grouping species into one "population" as splitters argue.

Regarding passage #18, the passage states: "Its proponents define a species as a group that is reproductively isolated from other groups, which means that there is no substantial interbreeding in the wild between members of the groups."

With this in mind, A and E can be swiftly eliminated.

To answer your question as to why D is the correct answer, we have to view it from a perspective that although bird species X and Y have different have physical differences, they likely have the genetics to interbreed. Physical attributes don't mean anything to the genetic side of things. It is possible that species X and Y could be a part of the same "group", it never states they are different species, just that they look different. If we approach the answer choice with the mindset that X and Y are a part of the same group, then maybe that "group" (X and Y) may be isolated from interbreeding with other groups/species, but not themselves. Because it was never stated that X and Y were two different species, it's possible that these "species" could be a part of the same group, which then again, allows for the interbreeding. As for the interbreeding portion, the passage states, "no substantial interbreeding", therefore interbreeding can occur, though not substantially.

Regarding passage #21, it's stated in the passage that splitters have the following perspective: "Splitters, on the other hand, tend to use the increasingly popular phylogenetic species concept, which defines a species as a "diagnosable" population, among which there is a pattern of ancestry and descent."

Answer choice C is a statement that coincides with the splitters. As splitters argue that species can be defined as a "diagnosable" population composed of several different species, then if a "species" goes extinct but it fell into this "population", then that species has surviving members.

To make it clear, splitters could argue this by stating that "although a specific 'species' went extinct, we categorized that 'extinct' species into a population (one big species), therefore, even though that 'species' is 'extinct', some members (of the population) can live on as that 'species' because they were originally grouped together.

I hope this make sense to a certain extent!

Hello I am interested in joining as well!

It's stated, "There are no naturally occurring strains of wheat that have Rhizobium bacteria living in their roots."

Therefore, if the wheat roots have Rhizobium, then it is not a natural strain of wheat. In LAWGIC: /Rhizobium → Natural

In LAWGIC /Natural → Rhizobium

The second sentence states, "The wheat sample sent to our lab was found to have Rhizobium bacteria on its roots."

Therefore, as shown in LAWGIC: /Rhizobium → Natural

Ultimately, the wheat sample that was sent to the lab was not a natural strain as Rhizobium bacteria was found within it.