Looking at the diagram and the corresponding answer choices, we need to identify the angle relationships for the numbered angles. Let’s break it down:

1. Angles 2 and 3: These are directly across from each other and are formed by two intersecting lines. This is a classic case of vertical angles.

   • Corresponding answer choice: A (vertical)

2. Angles 3 and 6: These angles are on opposite sides of the transversal but outside the two parallel lines, making them alternate exterior angles.

   • Corresponding answer choice: D (alternate exterior)

3. Angles 2 and 6: These angles are on the same side of the transversal and are outside the two parallel lines, which are classified as same-side exterior angles.

   • Corresponding answer choice: H (same-side exterior)

4. Angles 1 and 5: These angles are on opposite sides of the transversal and inside the parallel lines, known as alternate interior angles.

   • Corresponding answer choice: C (alternate interior)

Thus, the 4-letter code for the correct answer is: ADHC.

Would you like a more detailed explanation of any of the angle pairs? Here are some related questions to deepen your understanding:

1. What are the properties of vertical angles?
2. How do you identify alternate exterior angles in different diagrams?
3. Can same-side exterior angles be congruent?
4. How are alternate interior angles used in real-world applications?
5. What is the difference between alternate and corresponding angles?

Tip: Always look for intersecting lines and parallel lines when identifying angle relationships. This will help you classify angles correctly!