Which of the following is NOT one of the three highest military awards?

The Silver Star is indeed a prestigious military award, but it is not considered one of the highest military awards in the U.S. armed forces. The three highest military awards are the Medal of Honor, which is awarded for extraordinary bravery; the Distinguished Service Cross, which also recognizes heroism in combat but is ranked just below the Medal of Honor; and the Defense Distinguished Service Medal, awarded for exceptionally meritorious service.

The Silver Star, while highly regarded and given for gallantry in action, does not reach the same level of distinction as the three that are recognized as the highest honors. This categorization is crucial for understanding ranks within military awards, as it helps maintain a clear hierarchy reflecting the severity and context of the acts of valor being recognized.