a² – b² is equal to

⇒ Solving option (a)

⇒ (a – b)² = (a – b)× (a – b)

⇒ =(a× a – a× b – b× a + b× b)

=(a² – 2ab + b²)

⇒ Solving option (b)

⇒ (a – b)(a – b) = (a× a – a× b – b× a + b× b)

⇒ =(a² – 2ab + b²)

⇒ Solving equation (c)

⇒ (a + b)(a – b) = (a× a – a× b + b× a – b× b)

⇒ = (a² – b²)

⇒ Solving option (d)

⇒ (a + b)(a + b) = (a× a + a× b + b× a + b× b)

⇒ = (a² +2ab + b²)

Option (a) does not match to our solution.

Option (b) does match to our solution.

Option (c) does not match to our solution.

Option (d) does not match to our solution.

So, option (b) is correct answer.