The correct answer is B) one that flows at nearly right angles to your course steered. The reason is that a current flowing at nearly right angles to your course steered will have the greatest effect on the course made good for your vessel. This is because the sideways force of the current will push your vessel off its intended course, requiring constant adjustments to maintain the desired heading. In contrast, currents flowing in the same direction or opposite direction as your course will have a less pronounced effect on your course made good. The other options are incorrect because: A) a current flowing in the same direction will have less impact, C) a rotary current may have variable effects depending on the orientation, and D) a current flowing in the opposite direction will have less impact than a perpendicular current.