The line which crosses two lines is known as transversal and the pair of angles are formed on the opposite side of transversal but inside the two lines, that pair of angles are known as alternate interior angles.
if we see the picture C, D, E and F are the angles that are interior angles and the pairs that forms alternate interior angles are C and F and the other one is D and E.
From the given options, option B is right option.
C and F are pair of alternate interior angles.