Answer:
B) Additive Identity Property.
Step-by-step explanation:
Let us consider the definition of Additive Identity Property:
The additive identity property states that if you add a real number to zero or add zero to a real number, then you get the same real number back. The number zero is known as the identity element, or the additive identity.
In Step 5 we can see that,
[tex]0-12 = x - 36[/tex]
In Step 6 we get,
[tex]-12= x-36[/tex]
So basically, [tex]0-12 = -12[/tex]
We know that [tex]-12[/tex] is a real number and if a real number is added to 0, we get the real number back, so in step 6 we got -12.
Therefore, additive identity property yields step 6.