Seven boys Ash, Ben, Cam, Dim, Eff, Fin, and Gog are sitting in a straight line, facing north. Only two people sit to the left of Ash. Only three people sit between Eff and Ash. Ben sits third to the right of Cam. Dim sits to the immediate right of Fin. Cam sits at one of the extreme ends. How many people sit between Gog and Dim?

 Since only two people sit to the left of Ash and only three sit between Eff and Ash, means Ash must be at the 3rd place from the left and Eff must be at the extreme right end.  Since Cam sits at one of the extreme ends, Cam must be at the extreme left.  Ben sits third to the right of Cam.  Dim sits to the immediate right of Fin. Final arrangement is shown below. From the above arrangement, it is clear that three boys are sitting between Gog and Dim. Hence, the correct answer is (C).