C. s is your answer.
The sum of 2 angles on a straight line (supplementary angles) is 180°. Vertical angles (opposites where a line intersects) are equal.
The upper left and lower right angles where p crosses the other lines (q, r, t) are 105°.
180 - 105 = 75°
So the upper right and lower left angles are 75°. The lower left angle where p intersects s is 85°, so it is not parallel to the others.
Please let me know if you have any questions.