A is wrong you wouldn't say "is" you would say are.
B is wrong to because "was" is not the correct verb to use.
D is wrong because key, should be plural, keys
C is correct, because it has subject and verb agreement.
You mean about the place library?
A muffin is a spongy cake made with eggs and baking powder
Muffins vs cupcakes
cupcakes have a little smoother texture while muffins have a bit harder texture
Answer and Explanation:
The poem addresses the tragedy of a man who seeks an impossible dream. In this case, we can consider that the hoprizon that he pursues is an allegory for this dream, because the more the man walks, the more he tries he cannot reach the horizon that always goes further, that is, he never managed to achieve the dream you so desire.
The people around this man will say that his effort is useless, since reaching the horizon and the dream is impossible, but he desires it so strongly that he will continue to try and ignore everyone around him.