Coral island with a central lake is
(a) Atoll
(b) Fringing reef
(c) Barrier reef
(d) All the above.

Options

A. Atoll
B. Fringing reef
C. Barrier reef
D. All the above.

Answer

To solve the question "Coral island with a central lake is:", we can analyze the options provided:

1. **Understanding the Terms**:
- **Atoll**: An atoll is a ring-shaped coral reef, island, or series of islets that encircle a lagoon, which is a central body of water.
- **Fringing Reef**: This type of reef is directly attached to the shore of a landmass and does not have a lagoon.
- **Barrier Reef**: A barrier reef is similar to a fringing reef but is separated from the shore by a lagoon.
- **All of the above**: This option suggests that all previous options are correct.

2. **Identifying the Correct Option**:
- The question specifically mentions a "coral island with a central lake." This description fits the definition of an **atoll**, which has a lagoon (the central lake).
- **Fringing reefs** and **barrier reefs** do not have a central lake; they are types of reefs that are either attached to the shore or separated from it by a lagoon, respectively.

3. **Conclusion**:
- Since only the atoll fits the description of a coral island with a central lake, the correct answer is **(a) Atoll**.

### Final Answer:
The correct answer is **(a) Atoll**.