Final answer:
Congress impeached President Andrew Johnson for the removal of his Secretary of War without Senate approval. Option D is the correct answer.
Step-by-step explanation:
The correct answer is Option D: It impeached Johnson.
In response to President Andrew Johnson's removal of his Secretary of War without Senate approval, Congress took action to punish him. The House of Representatives quickly drafted a resolution to impeach him, making him the first U.S. president to be impeached. However, Johnson was not convicted by the Senate, so he remained in office.
This event highlighted the ongoing power struggle between Congress and the executive branch during the Reconstruction era.