Crown of teeth is covered by
(a) dentine
(b) enamel
(c) both (i) and (ii)
(d) none of these

Options

A. dentine
B. enamel
C. both (i) and (ii)
D. none of these

Explanation

To solve the question "Crown of teeth is covered by," we need to analyze the options provided:

1. **Understanding the Crown of Teeth**:
- The crown of a tooth is the visible part that is above the gum line. It is the part of the tooth that is exposed in the mouth.

2. **Identifying the Materials**:
- The crown is primarily covered by a specific type of tissue. The two main components of a tooth are enamel and dentine.
- **Enamel**: This is the outermost layer that covers the crown of the tooth. It is known for being the hardest substance in the human body, even harder than bone. Enamel is primarily composed of minerals, which contribute to its strength and durability.
- **Dentine**: This is the layer beneath the enamel and is softer than enamel. It supports the enamel but does not cover the crown.

3. **Evaluating the Options**:
- (a) Dentine: This is incorrect because dentine does not cover the crown; it lies beneath the enamel.
- (b) Enamel: This is correct as enamel is the outer covering of the crown of the tooth.
- (c) Both (i) and (ii): This is incorrect because while both dentine and enamel are parts of the tooth, only enamel covers the crown.
- (d) None of these: This is incorrect because we have identified that enamel does cover the crown.

4. **Conclusion**:
- The correct answer is (b) enamel, as it is the substance that covers the crown of the teeth.

### Final Answer:
(b) enamel