Answer:
Option A is the correct choice.
Explanation:
We have been given a graph of angles formed around a line and we are asked to choose the correct option that could be used in step 2 to prove that x equals 30.

We can see that angle ORP and angle ORN (3x+10) forms a linear pair as they are adjacent and formed by line PN intersected by line MO.
Therefore, the step 2 to prove that measure of x is 30 will be:
is linear pair of angles and option A is the correct choice.
Let us solve for x.
Since linear pair of angles add up-to 180 degrees, so we can set an equation as:







Hence proved.