A great circle can always be drawn through any two distinct points on the surface of the sphere.
Say the marksman will hit the points P1, P2, and P3. Draw a great circle through P1 and P2 dividing the sphere into two hemispheres. Since P1 and P2 are on the boundary of these hemispheres, they belong to both hemispheres. Now P3 can be on any of the two hemispheres. Hence, the three points will always be on the same hemisphere.
Probability, P = 1.0 answer [ C ]