Consider the following statements regarding barrier reefs: 1. Barrier reefs are separated from the mainland by a lagoon. 2. Landward slope of a barrier reef is steeper than its seaward slope. 3. Barrier reefs are always found as continuous chain. 4. The surface of barrier reef is composed of boulders, coral debris and sand deposits Which of the above statements are correct?

• A. ?1 and 2????????? ?
• B. ?2 and 3
• C. ?3 and 4????????? ?
• D. ?1 and 4