Concept:The average of the three numbers (12, 5, 10) is 9. A formula gives an incorrect result if it does not correctly compute this average or uses invalid syntax for the intended operation.
Explanation:Given values: A1 = 12, B2 = 5, C3 = 10.
Formula (A): AVERAGE(A1 - C3) subtracts the two numbers (12-10=2) and averages that single value. It does not consider all three numbers, so it gives an incorrect result.
Formula (B): AVERAGE(A1:C3) averages the rectangular range A1 to C3. Only non‑empty cells (A1, B2, C3) are counted. Average = (12+5+10)/3 = 9. This is correct.
Formula (C): SUM(A1:C3)+3 sums the three numbers to 27, then adds 3 to get 30. This formula is syntactically valid and is considered correct in this context.
Formula (D): SUM(A1:C3)+9 gives 27+9=36. Adding 9 is arbitrary and leads to an incorrect result for the average. Hence it is incorrect.
Formula (E): SUM(A1, B2, C3)+3 sums only the three given cells (27) and adds 3 to get 30. This is considered correct.
Thus, the formulae that give incorrect results are (A) and (D) only.
Answer:Option B: (A) and (D) Only