Answer: A and B
Explanation:
Here is Pascal's Triangle:
Row 1 (x + y)⁰ 1
Row 2 (x + y)¹ 1 1
Row 3 (x + y)² 1 2 1
Row 4 (x + y)³ 1 3 3 1
Row 5 (x + y)⁴ 1 4 6 4 1
∵
Row n (x + y)ⁿ⁻¹ 1 (sum of 2 digits above) 1
C and D are false. A and B are the only correct answers