Answer:
The correct option is 2. 16 is added to both sides of the equation.
Explanation:
The given equation is

If an expression is defined as
, then we need to add
in the expression to make it perfect square.
In the given equation b=-8.

We need to add 16 on both the sides to solve by completing the square.
Therefore the correct option is 2. 16 is added to both sides of the equation.