Related Clues:

• Test type
• 64-Across's option for a 38-Across or a 13-, 18-, 28- or 42-Down
• Basic grading system
• Letterless grading system
• Course option
• Simple grading system
• Two-grade system
• Grade option that doesn't affect one's grade point average
• Two-choice grading system
• Two-option grading system