Step 1: Beginning with Brahmā.
According to tradition, the knowledge of Ayurveda originated from Brahmā, the creator.
Step 2: Transmission to Dhanvantari.
Brahmā transmitted this knowledge through successive sages until it reached Lord Dhanvantari, considered the divine physician and an incarnation of Viṣṇu.
Step 3: Contribution of Suśruta.
Suśruta, a disciple of Dhanvantari, systematized the science of surgery in the Suśruta Saṁhitā.
Step 4: Contribution of Vāgbhaṭṭa.
Later, Vāgbhaṭṭa compiled the knowledge into texts like Aṣṭāṅgahṛdaya, which integrated earlier teachings.
Step 5: Correct chronological order.
Thus, the sequence is: Brahmā (D) → Dhanvantari (C) → Suśruta (A) → Vāgbhaṭṭa (B).