Hi Kennedv_!
Ok let's tackle this tricky question and do some B/E differentiation!
Let's start by breaking down the argument in the stimulus:
The conclusion comes after the "Hence" (a great conclusion indicator!):
C: We have a greater duty to protect the life of an individual whooping crane than an individual sandhill crane.
Why? Well, the author tells us it's because:
P: The life of any one whooping crane is more important to the preservation of the species than the life of any one sandhill crane is to the preservation of its species.
The question stem is asking us for a principle that conforms to this argument. So this is a Strengthen-Principle question. That means we need to find a principle that helps this argument out. Strengthening often just means that we need to make the link between the premises and the conclusion stronger. So in this case, we want to show that if the life of an individual whooping crane is more important to the survival of its species (in other words, if the premise is true), then we have a greater duty to protect the life of an individual whooping crane (then the conclusion is true).
Answer choice (B) gives us the principle we need: "The more important the survival of individual members is to the preservation of a species, the greater the duty to protect the lives' of that species' individual members." This matches our stimulus argument, which basically says that individual whooping cranes are more important to the survival of their species, so we have a greater duty to protect individual whooping cranes.
Answer choice (E) is similar, but the relationship is in the wrong direction: "There is a greater duty to protect one individual organism over another only if the former organism is a member of an endangered species and the latter organism is not." This tells us that being a member of an endangered species is necessary for prioritizing the survival of an individual of that species over another, but it doesn't tell us that being a member of an endangered species is sufficient for prioritizing an individual of that species over another. If you're familiar with conditional reasoning terminology, answer choice (E) is a Mistaken Reversal of what we need in the correct answer.
To sum up, we're looking for a rule that basically tells us that the premise is sufficient for the conclusion. To diagram:
Life of individual is more important to survival of the species
Greater duty to protect individual of that species
That's what answer choice (B) gives us.
Answer choice (E) is in the opposite direction:
Greater duty to protect individual of that species
Life of individual is more important to survival of the species
That doesn't help us out because we're trying to prove that we have a greater duty to protect individuals of a specific species.
It's totally fine that (B) doesn't specifically mention endangered species. What if 2 species were both endangered but one of them was MORE endangered. An individual from the more endangered species would be more important to the survival of its species and we would therefore have a greater duty to protect it. And what if neither of 2 species were endangered? We'd have a greater duty to protect whichever individual was more important to the survival of its species. It's all about how important they are to the survival of their species, not necessarily whether or not they are endangered.
There's not a conceptual difference between protecting "an individual of a species" and protecting "individuals of a species." Both phrases are referring to protecting individuals.
Hope this helps clarify a tricky question!
Best,
Kelsey
