Select the option that can be used as a one-word substitute for the given group of words.
A lively, cheerful outgoing person.

The correct option is Extrovert.

Let's break down the meaning of the given group of words and look at the definition of each option:
The phrase to substitute is: "A lively, cheerful outgoing person."

1. Extrovert: A person who is outgoing, socially confident, lively, and enjoys interacting with other people. This is the direct definition of the given description.

2. Introvert: A person who is typically reserved, quiet, and prefers solitary activities or spending time in quiet settings over active social gatherings.

3. Ambivert: A person whose personality exhibits characteristics of both introversion and extroversion, standing in the middle spectrum.

4. Orator: A person who is a highly skilled, eloquent, and professional public speaker.

Therefore, the most suitable one-word substitute is Extrovert.