Missiles can be broadly classified into ballistic and cruise missiles. Ballistic missiles are launched directly into the upper layers of the earth`s atmosphere, while cruise missiles fly close to the earth`s surface, following the terrain.

1. Agni-l: This is a ballistic missile developed by India. It`s designed to carry a nuclear payload, and it is not a cruise missile. So, the inclusion of this missile in options 1 and 3 makes those choices incorrect.

2. BrahMos: A joint venture between India and Russia produced this high-speed cruise missile, named BrahMos. It can fly at supersonic speeds and be launched from submarines, ships, aircraft, or land. Thus, any option without BrahMos (in this case, option 4) can’t be the correct answer.

3. Dhanush: Dhanush is a naval variant of the Prithvi missile and is categorized as a ballistic missile, so it is not a cruise missile.

With the above explanation, the correct answer should indeed be option 2: `2 only.`