The leaf of Citrus is a simple leaf.

Answer

### Step-by-Step Solution:

1. **Understanding Leaf Types**:
- Leaves can be classified as simple or compound. A simple leaf has a single blade, while a compound leaf consists of multiple leaflets attached to a single petiole.

2. **Identifying Citrus Leaf Structure**:
- The leaves of the Citrus plant are not simple; they are classified as palmate compound leaves. This means that the leaflets arise from a common point at the end of the petiole, resembling the fingers of a hand.

3. **Characteristics of Palmate Compound Leaves**:
- In palmate compound leaves, the leaflets spread out from the petiole like fingers from a palm. In the case of Citrus, there are typically multiple leaflets, but in some instances, two lateral leaflets may be suppressed, leaving only the central leaflet functional.

4. **Defining Unifoliate Compound Leaf**:
- When a palmate compound leaf has only one functional leaflet (due to the suppression of other leaflets), it is referred to as a unifoliate compound leaf.

5. **Conclusion**:
- Therefore, the statement that "the leaf of Citrus is a simple leaf" is incorrect. Instead, it is more accurate to describe it as a palmate compound leaf, specifically a unifoliate compound leaf if only one leaflet is functional.