The political scandal known as Whitewater centered on which allegation?

The political scandal known as Whitewater primarily centered on allegations regarding Bill Clinton's involvement in illegal real estate transactions before he became president. The case emerged when Clinton and his wife, Hillary, were implicated in an investment venture that was believed to have involved improper financial dealings and misconduct in the context of real estate development in Arkansas during the 1980s. The investigation into Whitewater ultimately expanded and led to various inquiries, but its roots are firmly planted in these real estate transactions involving the Clintons.

The other options, while notable in U.S. political history, relate to different scandals or issues. The allegations of sexual involvement with a White House intern relate to the Monica Lewinsky scandal, which, while politically impactful, is separate from the Whitewater case. Similarly, sexual harassment claims against Clarence Thomas are distinct and refer to the confirmation hearings of the Supreme Court nominee. Lastly, violations of campaign finance law by the Republican Party pertain to different political investigations and are not connected to the Whitewater allegations. Thus, the focus on illegal real estate transactions correctly identifies the core of the Whitewater scandal.