1 . 1-a2+2ab-b2

• A. $\left(1+a-b\right)\left(1-a+b\right)$
• B. $\left(1+a+b\right)\left(1-a+b\right)$
• C. $\left(1+a+b\right)\left(1-a-b\right)$
• D. $\left(1-a+b\right)\left(1-a-b\right)$

Answer: Option A

Explanation:

2 . 1-a2+2ab-b2

• A. (1+a+b)(1-a+b)
• B. (1+a+b)(1-a-b)
• C. (1+a+b)(1+a-b)
• D. (1+a-b)(1-a+b)

Answer: Option D

Explanation: