“Zenith” refers to the highest point or peak of something, such as success or achievement.
The synonym “pinnacle” also means the highest point of success, achievement, or excellence.
Thus, the correct answer is Option C.
Arun’s present age in years is 40% of Barun’s. In another few years, Arun’s age will be half of Barun’s. By what percentage will Barun’s age increase during this period?