I believe it's C, not 100% sure though.
You didn't give the options. However, i'll try.
To me, a stone cannot be ethical because it cannot suffer. Indeed, the capacity for suffering must be satisfied before we talk about interest in a meaningful way. For instance, nothing we could possibly do for a stone could make a difference in its welfare. It don't have interest. Whereas, we, humans have interest. Therefore we can be ethical because we are sentient beings that can be benifited or harmed. It's because we can experience pain as a result.
Hope this helps !
Photon
You get to give living things (animals or children) another chance at life, another chance at family.
Btw, love your icon
