Explanation:

- Urja Sanchay Policy: This option does not correctly relate to the current procurement scheme by the Ministry of Power. It’s not associated with a major existing energy policy.

- Shakti Policy: This initiative is indeed linked with coal allocation and power sector reform, but it is not the correct policy for the 4500 MW power procurement scheme.

- Nai Urja Policy: This is not related to existing policies or schemes in the power sector for the Ministry of Power's current procurement activity.

- Gatishakti Policy: This program is intended to enhance infrastructure planning and coordination rather than specific power procurement.

The correct policy associated with the scheme for procurement of aggregate power of 4500 MW is under: Shakti Policy