What is your MVP?

Pre-order: collecting pre-orders (no development started) through your contacts, lending page, demonstration video, or social network announcement.
Concierge - manual service provision for checking a demand instead of developing/coding your complete solution.
The primary function MVP - you have only one function but the most important for the market.
Lead-generation MVP - posting articles raising the problem on resources where is your target audience sitting.
A fully developed solution already exists.