Answer:
C) Subtraction property of equality.
Explanation:
Given that, two lines
and
intersect to make pairs of vertical angles:
and
.
Kindly refer to the attached image for details of the given angles and lines.
Proof that
:

Here, subtraction property of equality is used in the last step shown in the above.
As per the Subtraction property of equality, when some value is subtracted from both the sides of the equality, equality remains the same.