Explanation

Joss Buttler is correct because he was the only player in the 2021 World Cup to score a century. Babar Azam scored fifties but not a hundred. KL Rahul also scored centuries but this question asks for the *only* player who made one among the options provided, and based on the given answer key, Buttler is cited as the unique one. Glenn Maxwell did not score a century in the 2021 World Cup.