Explanation:

- Manuscripts have historically been created on materials that were readily available and easy to write on.

- Option:1, marbles: Marbles are hard stones, unsuitable for writing on directly due to their solid and slippery surface.

- Option:2, palm leaf: Palm leaves were a prevalent writing medium in ancient India and Southeast Asia. They were readily available, easy to inscribe upon, and durable when properly prepared.

- Option:3, tulsi leaves: Tulsi, or holy basil, has spiritual significance but its fragile and small leaves are impractical for writing.

- Option:4, iron: Iron is a hard metal, not a useful or common surface for traditional manuscript writing.