Final answer:
The U.S. did not invade Iraq in 2003 to protect Afghanistan; the reasons were the belief in Iraq's possession of WMDs, the desire to remove Saddam Hussein, and to promote peace and stability.
Step-by-step explanation:
The reason that WAS NOT a cause for the U.S. invasion of Iraq in 2003 is option a. to protect Afghanistan. The Bush administration made the decision to invade Iraq based on several key factors: the belief that Iraq possessed weapons of mass destruction (WMDs), the desire to remove Saddam Hussein from power, and the aim to promote peace and stability in the region. Additionally, there were unfounded claims that Iraq had connections to al-Qaeda and that Hussein's regime was a significant threat to national security. The options to destabilize Pakistan or to protect Afghanistan were not stated reasons for the invasion. Over time, it was revealed that Iraq did not actually have WMDs, and there was not a meaningful connection between Al Qaeda and Iraq, leading to widespread criticism of the invasion."