The question asks to identify the specific inscription of Emperor Asoka that details his concept of 'Dharmavijaya'. 'Dharmavijaya' refers to conquest through righteousness or moral law, a significant shift from military conquest.
The XIII Rock Edict provides an account of 'Dharmavijaya'.
Therefore, the XIII Rock Edict is the correct source for information regarding Asoka's concept of Dharmavijaya.