Step 1: What is life expectancy.
Life expectancy is the average number of years a person is expected to live, based on current data.
Step 2: What pushes it up.
Small, rich countries with very good healthcare usually top the list.
Step 3: The leader.
Monaco, a tiny but wealthy city state, regularly reports the highest life expectancy in the world, often near or above 89 years.
Step 4: Remove others.
South Korea, Hong Kong, and San Marino all rank high, but Monaco stays at the very top.
Step 5: Confirm.
Because of its strong healthcare and high income, Monaco leads the global figures.
Step 6: Conclusion.
So the country with the highest life expectancy is Monaco.
Answer: Monaco