(A) 88
(B) 100
(C) ** 59
(D) 60
EXPLANATIONS BELOW
Concept note-1: -The oldest president at the end of his tenure was Ronald Reagan at 77; this distinction will eventually fall upon Joe Biden, who is currently 80.
Concept note-2: -Obama left office on January 20, 2017, and continues to reside in Washington, D.C. His presidential library in Chicago began construction in 2021. Since leaving office, Obama has remained active in Democratic politics, including campaigning for candidates in various American elections.