Yes . Because it's not "you're" cause you are not gonna say "how did you are test go?"
Its C Their because their is the only option refering correctly to the sentence. Read the sentence out loud with option C and you will "C" that it is correct lol
The answer is
“A. The injustice of discrimination.”
The reason for this is that the dog is at old age, stinky and is about to die. And in the book Carlson believes his useless for that reason, and the dog was discriminated for it. The author expressed how society treats (or discriminate) people of old age, person with disabilities and minorities.