Final answer:
The Blood Stripe worn by Marine Corps NCOs and officers symbolizes the blood shed by Marines in battle, particularly commemorating those who fell during the Battle of Chapultepec.
Step-by-step explanation:
The significance behind the Blood Stripe worn on NCO and Officer uniforms in the United States Marine Corps is b) Symbolizes blood shed in battle. This red stripe seen on the dress pants of the Marine uniform honors Marine Corps officers and Non-Commissioned Officers (NCOs) who have lost their lives in battle. It specifically commemorates the high number of casualties suffered by Marine Corps personnel during the Battle of Chapultepec during the Mexican-American War in 1847.
While your question touches upon an aspect of the military, the information provided regarding the Red Cross and the segregation of blood during World War II, as well as the efforts by the NAACP, relates to a different aspect of military history. That information is about the struggle for racial equality in the armed forces, exemplified by the heroic contributions of the Tuskegee Airmen and the 761st Tank Battalion, rather than the origin of the Blood Stripe itself.