Consider the given equation 
We will solve this equation by completing the square method.
Consider the coefficient of 'x', divide it by '2'. then adding and subtracting the square of this number in the given equation.
Coefficient of 'x' = -8
By dividing it by '2', we get -4
Taking the square of '-4' = 16
Adding and subtracting '16' from the given equation.

So, 
This equation shows one of the step used in solving the equation by completing the square method.
Therefore, option 1 is the correct answer.