What must a French club prove to receive training compensation when a player moves before age 23?

To receive training compensation when a player moves before the age of 23, a French club must demonstrate that they offered a contract to the player at least 30 days prior to the expiration of their current contract. This requirement is in place to ensure that clubs are actively pursuing the retention of their young players and are making a formal effort to continue the player's development within the club.

If a club fails to provide this evidence, they may forfeit their right to claim training compensation. Training compensation is meant to acknowledge the investment made by the player's training club in developing the player. This helps safeguard the clubs' interests in youth development while also encouraging them to maintain connections with their trained players.

The other options suggest various conditions that do not align with the established rules for training compensation. Therefore, the necessity of offering a contract 30 days prior is a clear condition that aligns with FIFA’s regulations on player transfers and training compensation.