Nothing in the stimulus suggests that not all animals "should" be given rights. This is a value judgment that isn't supported by the stimulus, which is simply descriptive.

We can't infer this from the stimulus. This answer choice suggests that one can only bestow rights on animals by taking a broad definition of "living things," which isn't what the stimulus says. The stimulus just describes the consequences of defining "living things" broadly versus narrowly, without claiming that either one is a better option, let alone the only option that allows rights to be extended to animals.

This answer choice would be correct if it said that defining the scope of "living things" interfered with every attempt to establish animal rights based merely on the fact that animals are living things. As it stands, the stimulus doesn't actually tell us about every attempt to establish animal rights — just the attempt to establish animal rights based on one specific premise. So we can't infer this answer choice from the stimulus.

While this might seem like a bit of a jump from the stimulus, notice what this answer choice is specifically talking about: a successful attempt to establish rights for all animals.

Based on the information in the stimulus, there are two likely possibilities. Establishing rights for all animals could be based only on the premise that animals are living things, if we take a broad definition of "living things" that also includes some plants. On the other hand, if we take a narrow definition of "living things" — the only alternative scenario we know about — and still somehow guarantee rights for all animals, we know we can't be relying only on the premise that animals are "living things," since the narrow definition of "living things" excludes some animals. We must be relying on some additional premise.

So this answer choice is strongly supported by the stimulus.

The stimulus never suggests that the fact that animals are living things is "irrelevant" to whether they should be accorded rights. It just describes a difficulty with establishing animal rights based only on that premise.