Explanation:

- Throng: A large group of people or things gathered closely together.

- Option 1 - Elegy: A poem or song expressing sorrow or lamentation, especially for someone deceased. It's unrelated to a group or gathering.

- Option 2 - Vast: Refers to something immense in size or extent, often used to describe landscapes or spaces, not groups.

- Option 3 - Crowd: A large number of people gathered closely together, similar in meaning to 'throng'.

- Option 4 - Separation: The act of being moved or divided away from something else. It's the opposite of gathering or coming together.