(A) Hillary Clinton
(B) Donald Trump
(C) Chuck Schumer
(D) ** Joe Biden
EXPLANATIONS BELOW
Concept note-1: -On August 23, 2008, via text message, the Obama campaign announced that the then-presumptive Democratic presidential nominee chose Senator Joe Biden as his vice-presidential running mate.
Concept note-2: -Obama–Biden ticket Following U.S. Democratic presumptive presidential nominee Barack Obama’s selection of Biden, the Senator’s vice-presidential general election campaign began. During the campaign, he used his political experience to complement Obama, and debated Republican Vice Presidential nominee Sarah Palin.
Concept note-3: -The day after Obama’s acceptance speech at the Democratic National Convention, Obama’s Republican opponent, Arizona Senator John McCain, announced his selection of Alaska Governor Sarah Palin as his running mate.
Concept note-4: -Along with his running mate, Vice President Joe Biden, Obama was opposed in the general election by former Massachusetts Governor Mitt Romney, along with various minor candidates from other parties. The election took place on Tuesday, November 6, 2012.