One of the great difficulties in establishing animal rights based merely on the fact that animals are living things concerns scope.
Statements
It's hard to establish animal rights based only on the fact that animals are "living things", because how you define "living things" will make a big difference.
If you define it too broadly, you'll end up assigning rights to a head of lettuce (living organisms that we wouldn't normally consider animals).
If you define it too narrowly, you'll end up denying rights to organisms that are, at least biologically, considered animals.
Evaluate
If we're scanning for Conditional / Causal / Quantitative / Pivot type stuff, we may notice that the 2nd and 3rd sentences are conditionals.
If defined broadly → bound to bestow rights on non-animals
If defined narrowly → apt to refuse rights to things that are animals
Are those two triggers exhaustive?
Meaning, are we forced to fire one or the other? Is any definition of "living things" going to be broad or narrow?
Hmm, it's seems pretty close, since broad and narrow are pretty close to logical opposites. If it said "too broadly" / "too narrowly", then there's plenty of room in the middle for "just right". But since this is just "broadly vs. narrowly", it sounds like we're probably firing one or the other trigger.
Goal
It's hard to know what to predict here, but the big themes are - how to define "living things" has a causal impact on making it hard to establish animal rights - it sounds like we're going to either include too many or leave some out.