Select the option that can be used as a one-word substitute for the given group of words.

A person who thinks that bad things are more likely to happen or who emphasises the bad part of a situation

Pessimist

The one-word substitute for "a person who thinks that bad things are more likely to happen or who emphasizes the bad part of a situation" is pessimist.

• Misanthropist is a person who dislikes or distrusts humankind.
• Complainer is a person who frequently complains about things.
• Pessimist is a person who tends to see the negative side of things and expects the worst.
• Optimist is a person who tends to see the positive side of things and expects the best.

Pessimist is the most appropriate word for the given group of words because it specifically refers to someone who thinks that bad things are more likely to happen or who emphasizes the bad part of a situation. It is derived from the Latin word pessimus, meaning "worst."