Explanation

Reunion Island in the Indian Ocean is a classic volcanic island, formed by hotspot volcanism and still active through the Piton de la Fournaise volcano. The Andaman and Nicobar Islands are primarily of tectonic (subduction-related) origin, though they include the volcanic Barren and Narcondam islands; Lakshadweep and the Maldives are coral atolls built on subsiding volcanic bases, not volcanic islands themselves. The island of clearly volcanic origin among the options is therefore Reunion, option (A).