A California driving instructor is working with an adult student who has significant driving anxiety. What learning theory principle should guide the instructor's approach?

1. Immersion therapy—place the student in the most challenging driving scenarios immediately
2. Zone of Proximal Development—work slightly beyond the student's current comfort level with appropriate support
3. Allow the student to only practice what they are already comfortable with
4. Standardized approach—all students must follow the same rigid curriculum regardless of anxiety levels