Fill up the gap with aappropriate words. 

Neil Armstrong was________first man to walk on _______Moon. 

Correct option is C

• "The first man": We use "the" with superlatives (like "first") to indicate something specific and unique.

• "The Moon": "Moon" refers to Earth’s natural satellite, which is a specific celestial body, so "the" is used.
• The correct sentence will be : Neil Armstrong was the first man to walk on the  Moon.​