Question 810Navigation General

The correct answer is D) The telescope not parallel to the frame. The error of collimation in a sextant is caused by the telescope not being parallel to the frame of the sextant. This means that the line of sight through the telescope is not aligned with the plane of the frame, leading to inaccurate angle measurements. The other options are incorrect because they do not directly cause the error of collimation. Option A refers to the perpendicularity of the frame and index mirror, which affects the index error. Option B refers to personal error, which is not a physical adjustment of the sextant. Option C refers to the perpendicularity of the frame and horizon glass, which affects the horizon mirror.