To answer this question, we need to look at the T20 International career of each player mentioned and determine who has scored the maximum number of fifties.
Option A) MS Dhoni - While MS Dhoni is a highly accomplished player, he is not known for his prolific scoring in T20 Internationals. Therefore, it is unlikely that he has scored the maximum number of fifties in this format.
Option B) Yuvraj Singh - Yuvraj Singh is a talented player who has had some memorable innings in T20 Internationals. However, he has not been as consistent as some other players in terms of scoring fifties. Therefore, it is unlikely that he has scored the maximum number of fifties.
Option C) Gautam Gambhir - Gautam Gambhir is a former Indian cricketer who has had a successful career in T20 Internationals. He has been known for his consistent batting and ability to score fifties. Therefore, it is possible that he has scored the maximum number of fifties in this format.
Option D) Rohit Sharma - Rohit Sharma is a current Indian cricketer who is known for his explosive batting in T20 Internationals. While he has scored numerous centuries in this format, it is unclear if he has scored the maximum number of fifties.
The correct answer is C) Gautam Gambhir. He has scored the maximum number of fifties in T20 Internationals.