- A13 only
- B12 or 18
- C17 or 18
- D12 or 13
Step-by-Step Solution
Let Mathematics = , so Science . Then → → → → , so or 13. BOTH work: 12 and 18 give , and 13 and 17 give . Reporting "13 only" throws away an equally valid root — a root may only be rejected when the CONTEXT forbids it, and both marks here are legal. "12 or 18" mixes one subject with the other; "17 or 18" gives the Science marks.
Answer: D) 12 or 13