Final answer:
The Navy Cross uses "For extraordinary heroism..." as the opening phrase in its citations to recognize United States Navy and Marine Corps personnel for valor in combat.
Step-by-step explanation:
The medal that uses "For extraordinary heroism..." as the opening phrase in the citation is the Navy Cross. This is the United States Navy and Marine Corps' second-highest military decoration for valor that is awarded to members of the United States Navy and Marine Corps, and occasionally to members of other services, for extraordinary heroism in combat. The Navy Cross is awarded for extraordinary heroism not justifying the award of the Medal of Honor. It is second in precedence only to the Medal of Honor and is equivalent to the Army's Distinguished Service Cross and the Air Force Cross.