Choose the correct statements about the islands of India.
a. Lakshadweep Islands are composed of coral islands.
b. Andaman and Nicobar islands are composed of coral islands.
c. It is believed that Lakshadweep islands are an elevated portion of submarine mountains.
d. It is believed that Andaman and Nicobar islands are an elevated portion of submarine mountains.

Comparing the structural origins of the major island groups of India:
* Lakshadweep Islands: Situated in the Arabian Sea, these islands are composed entirely of coral deposits (atolls), making statement (a) correct and statement (c) incorrect.
* Andaman and Nicobar Islands: Situated in the Bay of Bengal, it is believed that these islands are an elevated portion of submarine mountains (an extension of the Arakan Yoma range), making statement (d) correct and statement (b) incorrect.