Fill in the blanks and select the correct option.
• The join of two adjacent vertices is called an __P__
• A __Q__ is one that does not cross itself.
• Two or more distinct lines meeting at a point are called __R__ lines.

Options

A. `{:(P,Q,R),("Diagonal","Simple curve","Concurrent"):}`
B. `{:(P,Q,R),("Edge","Curve","Parallel"):}`
C. `{:(P,Q,R),("Diagonal","Curve","Parallel"):}`
D. `{:(P,Q,R),("Edge","Simple curve","Concurrent"):}`

Answer

To solve the question, we need to fill in the blanks with the correct terms based on the definitions provided. Let's break it down step by step.

### Step-by-Step Solution:

1. **Identify the first blank (P)**:
- The statement is: "The join of two adjacent vertices is called an __P__."
- In geometry, when we connect two adjacent vertices, we form a line segment. Therefore, the answer for P is **"edge"**.

2. **Identify the second blank (Q)**:
- The statement is: "A __Q__ is one that does not cross itself."
- A curve that does not cross itself is known as a simple curve. Thus, the answer for Q is **"simple curve"**.

3. **Identify the third blank (R)**:
- The statement is: "Two or more distinct lines meeting at a point are called __R__ lines."
- When two or more lines meet at a single point, they are referred to as concurrent lines. Therefore, the answer for R is **"concurrent"**.

### Final Answers:
- P: edge
- Q: simple curve
- R: concurrent

### Summary:
- The join of two adjacent vertices is called an **edge**.
- A **simple curve** is one that does not cross itself.
- Two or more distinct lines meeting at a point are called **concurrent** lines.

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