Dana Carvey famously portrayed President George H. W. Bush on Saturday Night Live while Bush was in office.
Carvey began performing the impression in 1987, when Bush was still vice president under Ronald Reagan. The portrayal became especially prominent during Bush’s 1988 presidential campaign and presidency, often emphasizing Bush’s genial manner, clipped delivery, and phrase “a thousand points of light.”
The impression was more than a standard political parody. Bush reportedly enjoyed Carvey’s performance and later imitated it himself during Gerald Ford’s funeral. After Bush lost the 1992 election, he invited Carvey to the White House Christmas party, and the two developed a long friendship.
The other options are associated with different SNL political impressions. Phil Hartman was known for Bill Clinton and Ronald Reagan, Darrell Hammond became strongly associated with Bill Clinton, and Kevin Nealon did not originate the defining Bush impression. Fred Armisen later played Bush in a 2005 cold open, but Carvey is the canonical answer for Bush during his presidency.