During which operation was Shock and Awe unleashed by the US?

The correct answer is indeed Operation Iraqi Freedom, which commenced in March 2003. The "Shock and Awe" campaign was a key component of this operation, designed to quickly overwhelm Iraqi forces and diminish their will to fight through a massive display of air power. This strategy involved an extensive bombing campaign aimed at critical military and government infrastructure, showcasing the advanced capabilities of the U.S. military.

Operation Desert Storm, conducted in 1991 to drive Iraqi forces out of Kuwait, was also marked by significant air power but did not utilize the specific Shock and Awe strategy characterized by the 2003 invasion of Iraq. Operation Enduring Freedom primarily focused on combatting terrorism, particularly in Afghanistan following the September 11 attacks, and did not engage in the same style of pervasive aerial bombardment against a national military target as seen in Iraqi Freedom. Operation Southern Watch was primarily a post-Gulf War enforcement operation in Iraq, overseeing the no-fly zones, but it did not involve a large-scale invasion or any kind of Shock and Awe strategy.

Overall, the scale, execution, and intent behind the Shock and Awe campaign were uniquely aligned with the objectives of Operation Iraqi Freedom, making it the correct choice.