C. First of all, if someone says your dream is impossible, they're wrong.
Explanation:
A claim can be defined as an assertion made by an individual without providing a proof or evidence to back it up and as such may be false.
Basically, a claim is an opposite of a fact, statement of truth or factual statements containing evidences and proofs.
The best example of a claim is;
First of all, if someone says your dream is impossible, they're wrong. This is a claim because a dream can either be possible or impossible depending on the abilities or willfulness of the person involved.
The other options (examples) mentioned below are all examples of facts;
You can’t prove that something is impossible—all you know is that [it] hasn’t been done yet.People said no one could scale Mount Everest, but in 1953, Sir Edmund Hilary and Tenzing Norgay gazed down upon the world from its summit.People said that man could not fly, but in 1903, Orville and Wilbur Wright made the first sustained powered flight in a heavier-than-air machine.