The correct options are
B The mainland tapers down towards the south.
C The north and north-eastern regions are filled with young fold mountains.
D The mainland divides the ocean into two seas.
India has the young fold mountains called the Himalayas that covers the north and the north-eastern regions. Progressing towards the south, the mainland tapers to divide the Indian Ocean into two seas. Maldives is a country with a group of islands which is situated to the south of Lakshadweep.