Who is the current President of the United States?

The correct answer is Joe Biden, who has been serving as the President of the United States since January 20, 2021. He was elected during the 2020 presidential election and is a member of the Democratic Party. Joe Biden's presidency follows years of political experience, including serving as Vice President under Barack Obama from 2009 to 2017 and as a U.S. Senator from Delaware for several decades.

The other options represent individuals who held the office in the past. Donald Trump was the President before Biden, serving from January 20, 2017, to January 20, 2021. Barack Obama served from January 20, 2009, to January 20, 2017, and George W. Bush was in office from January 20, 2001, to January 20, 2009. None of these individuals are currently serving as President, which highlights the importance of understanding the timeline and current events in U.S. politics.