Which DOC in Marche is allowed to use a little Sangiovese in its Montepulciano-based wine?

The Rosso Piceno DOC is recognized for allowing the inclusion of a small proportion of Sangiovese in its wines, which are primarily based on Montepulciano. This characteristic enhances the wine's complexity and can add to its aromatic profile. The blending rules within Rosso Piceno DOC provide flexibility, enabling producers to incorporate Sangiovese, which complements the robust nature of Montepulciano with its bright acidity and red fruit flavors.

Conversely, while Conero DOCG is associated with Montepulciano, it primarily emphasizes the use of Montepulciano and does not have the same allowances for Sangiovese as part of its regulations. Verdicchio dei Castelli di Jesi DOC is primarily focused on white wines made from Verdicchio grapes, thus having no relevance to a blend with Sangiovese. Orvieto DOC also focuses on white wines and does not pertain to Montepulciano-based blends. Therefore, the identification of Rosso Piceno DOC as the correct answer is grounded in its specific guidelines that permit the blending of Sangiovese alongside Montepulciano.