On the basis of their A____ and B____ there are three types o tissue systems.

Answer

To answer the question, "On the basis of their A____ and B____ there are three types of tissue systems," we need to identify what A and B represent in the context of plant tissue systems.

### Step-by-Step Solution:

1. **Identify the Context**: The question pertains to the classification of tissue systems in plants. We know that plants have various types of tissue systems.

2. **Recall the Types of Tissue Systems**: There are three main types of tissue systems in plants:
- Epidermal Tissue System
- Ground Tissue System
- Vascular Tissue System

3. **Determine the Basis of Classification**: The classification of these tissue systems is based on two main criteria:
- **A**: Structure
- **B**: Location

4. **Final Answer**: Therefore, the complete answer to the question is:
- On the basis of their **structure** and **location**, there are three types of tissue systems.