What Role Does the Claim That Nonhuman Animals Can Feel

What role does the claim that nonhuman animals can feel pain play in this paper?

A) Steinbock argues for this claim.
B) Steinbock argues against this claim.
C) Steinbock argues that this fact settles the issue of whether it's justified to privilege human interests over nonhuman interests.
D) Steinbock argues that this fact does not settle the issue of whether it's justified to privilege humans' interests over nonhumans' interests.