Explanation:

- Infallible: A term used to describe someone or something that is incapable of making mistakes or being wrong. It suggests perfection in judgment or performance.

- Pure: Often used to describe something that is clean, untainted, or morally unblemished. It doesn’t specifically relate to making mistakes.

- Optimist: Refers to a person who generally expects positive outcomes and looks on the bright side. This term is about a mindset, not the ability to avoid errors.

- Naive: Describes someone who is inexperienced or innocent, often lacking in judgment or sophistication. It implies vulnerability to making mistakes.