The required "option B) xy = 12" is correct.
Explanation:
Check the options:
A) 4x = 12
Dividing both sides by 4, we get
⇒ x = 3
4x = 12 is a linear equation in one variable x.
B) xy = 12
xy = 12 is a non-linear equation.
D) 3x - 6y = 12
Dividing both sides by 3, we get
⇒ x - 2y = 4
3x - 6y = 12 is a linear equation in two variables x and y.
Thus, the required "option B) xy = 12" is correct.