End of semester geometry Semester A question 6 Select the correct answer.
Given:

Prove:

By the linear pair theorem, is supplementary to . Since , by the definition of congruence, . Applying the substitution property of equality, . Simplifying the equation, .

What step is missing from this proof?

A.
is supplementary to by the transitive property.
B.
by the definition of supplementary angles.
C.
by the definition of congruence.
D.
by the linear pair theorem.