Choose the correct one word substitute for the following:
"One who looks at the bright side of things."

The correct answer is Option A (optimist).

Key Points:
• Concept: One Word Substitutions.
• Explanation: An 'optimist' is a person who tends to be hopeful and looks at the positive or bright side of things.
• Other Terms:
• 'Pessimist': One who looks at the dark or negative side of things.
• 'Cynic': One who believes people are motivated purely by self-interest.
• 'Humanist': An advocate of human welfare or humanism.
• Official Key: Option 1 ('optimist') is the official answer.
• Key Takeaway: Remember: 'Optimist' = looks at the bright side; 'Pessimist' = looks at the dark side.