A, B, and C Are Co-Owners of a Parcel of Land

A, B, and C are co-owners of a parcel of land. A sells his aliquot part of the whole property without the consent of B and C. Is the sale valid?

A) Yes, it is valid, because the right of alienation is one of his rights over the ideal shares in the co-ownership.
B) No, it is invalid, because the consent of his co-owners is material for the sale to be valid.
C) Yes, it is valid because the co-owners did not object when he sold his part.
D) No, it is invalid because a co-owner cannot sell his part to third person without offering it first to his co-owners.