Select the word which means the same as the group of words given.

One who is preoccupied with his own interests

Egoist

The word which means the same as the group of words "one who is preoccupied with his own interests" is egoist.

• Egoist means a person who is excessively conceited or absorbed in themselves.
• Pessimist means a person who tends to see the worst aspect of things or believe that the worst will happen.
• Atheist means a person who disbelieves or lacks belief in the existence of God or gods.
• Optimist means a person who tends to be hopeful and confident about the future or the success of something.

The word egoist is the most appropriate because it specifically refers to someone who is focused on their own needs and desires. The other words do not have the same connotation of self-absorption.