The answer is letter b.
During this period the U.S. set up a blockade to prevent Russian ships
from passing to Cuba. The U.S. was
alarmed after photos from a spy plane showed Russian missiles on Cuban
soil. This heightened American fears
that Russia would invade through Cuba and use the missile already set up
there. At this point in time, the world
was on the verge of nuclear war. Both
side weighed their options. After a tense period, secret negotiations brought
an end to the conflict. The Russians
withdrew their missiles from Cuba and the U.S. withdrew their missiles from
Turkey.
