Step 1: Priest of Ṛgveda.
The Ṛgveda consists of hymns and mantras recited by the Hotā priest. Hence A - II.
Step 2: Priest of Yajurveda.
The Yajurveda deals with sacrificial rituals, performed by the Adhvaryu priest. Hence B - IV.
Step 3: Priest of Sāmaveda.
The Sāmaveda is musical and chanted by the Udgātā priest. Hence C - I.
Step 4: Priest of Atharvaveda.
The Atharvaveda is associated with magical hymns and healing, and the supervising priest is Brahmā. Hence D - III.
Step 5: Conclusion.
Thus, the correct match is A - II, B - IV, C - I, D - III.