Final answer:
About 95 percent of U.S. House incumbents won reelection in recent years, highlighting the significant incumbency advantage that favors sitting members during elections.
Step-by-step explanation:
In recent years, about 95 percent of U.S. House incumbents won reelection. This high reelection rate reflects what is known as the incumbent advantage or incumbency effect, which benefits sitting members of Congress during elections. The incumbents often have significantly higher name recognition and access to fundraising compared to challengers, contributing to their reelection success. Data from the Congressional Election Data, 1970-2012, similarly shows that nearly 92 percent of African American congressional incumbents were reelected, indicating that this incumbency advantage is consistent across racial lines within the House. Therefore, the correct answer is d. 95.