Which one of the following statements best reflects the idea behind the "Fractional Orbital Bombardment System" often talked about in media?

Which one of the following statements best reflects the idea behind…

A hypersonic missile is launched into space to counter the asteroid approaching the Earth and explode it in space.
A spacecraft lands on another planet after making several orbital motions.
A missile is put into a stable orbit around the Earth and deorbits over a target on the Earth.
A spacecraft moves along a comet with the same speed and places a probe on its surface.

Answer

(a) Incorrect. FOBS is a nuclear/missile delivery concept, not an asteroid-defence system using hypersonic missiles in space.
(b) Incorrect. This describes a spacecraft making orbital revolutions before landing on another planet; it has nothing to do with FOBS.
(c) Correct. In a Fractional Orbital Bombardment System, a missile is launched into a partial/low Earth orbit and then deorbited toward a target on Earth; the idea is to approach unpredictably and evade some early-warning systems.
(d) Incorrect. This refers to comet rendezvous/probe placement, like deep-space mission operations, not orbital bombardment.

Answer: (c)