Which of the following 'suffixes' used for units of classification in plants indicates a taxonomic category of 'family'?

Options

A. `-`aceae
B. `-` ae
C. `-`ales
D. `-`psida

Explanation

To determine which suffix indicates the taxonomic category of 'family' in plants, we can analyze the provided options step by step.

### Step-by-Step Solution:

1. **Understanding Taxonomic Hierarchy**:
- The taxonomic hierarchy in biology includes several ranks: Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species. The family is the fifth rank in this hierarchy.

2. **Identifying the Suffix for Family**:
- In botanical classification, the suffix that indicates the taxonomic category of 'family' is typically "-aceae". For example, the family name for roses is "Rosaceae".

3. **Analyzing the Options**:
- **Option A: -aceae**: This is indeed the suffix used for the family category in plants.
- **Option B: -ae**: This suffix is used for the taxonomic category of 'class'.
- **Option C: -ales**: This suffix indicates the taxonomic category of 'order'.
- **Option D: -idae**: This suffix is also used for the taxonomic category of 'class' in some contexts.

4. **Conclusion**:
- Based on the analysis, the correct suffix that indicates the taxonomic category of 'family' in plants is **Option A: -aceae**.

### Final Answer:
The suffix used for units of classification in plants that indicates a taxonomic category of 'family' is **-aceae**.