Answer: Option B
Answer: (b)
Given, 7 * 7 * 2 * 1 = 12
Let us check all the options one by one.
From option (a),
putting the signs in given equation, we get
7 x 7 - 2 ÷ 1 = 12
⇒ 7 x 7 -2 = 12
⇒ 49 - 2 = 12
⇒  47 = 12
⇒ LHS ≠ RHS
So, option (a) is incorrect.
From option (b),
putting the signs in given equation, we get
7 + 7 - 2 x 1 = 12
⇒ 7 + 7 -2 = 12
⇒ 14 -2 = 12
⇒  12 = 12
Hence, option (b) is correct and there is no need to check remaining options.