When multiple survivors wearing lifejackets are in cold water awaiting rescue, why should they adopt the 'Huddle' (Posición de Agrupamiento)?

1. To form a human anchor and prevent drifting with the current
2. To press their torsos together in a tight circle, conserving body heat, boosting morale, and creating a larger visual target for rescuers
3. To enable one person to stand on the shoulders of others to see the shore
4. To share a single lifejacket among several people