Explanation:

- Sceptic: Someone who often doubts or questions accepted opinions.

- Option 1: Doubter: This is close in meaning to sceptic as it involves questioning or having doubts.

- Option 2: Believer: This is typically someone who accepts something as true or has faith, making it the opposite of someone who questions or doubts.

- Option 3: Disbeliever: This involves actively rejecting or not believing, more akin to sceptic in a lack of belief.

- Option 4: Receiver: This is someone who receives, unrelated to the concept of belief or scepticism.

Correct Answer: Believer