Final answer:
When observing steady red and green lights ahead and at the same altitude during a night flight, it indicates the other aircraft is approaching head-on, with the red light on the left wingtip and the green light on the right wingtip.
Step-by-step explanation:
During a night flight, if you observe steady red and green lights ahead and at the same altitude, the general direction of movement of the other aircraft is approaching head-on. In aviation light signal conventions, the red light is on the left wingtip and the green light is on the right wingtip. When you see both steady and at the same altitude in front of you, it indicates that the other aircraft's left side is on your right and vice versa, meaning you are facing each other. Therefore, the correct answer is A. The other aircraft is approaching head-on. When observing steady red and green lights ahead and at the same altitude during a night flight, the general direction of movement of the other aircraft can be determined based on the color of the lights. In aviation, red lights are usually located on the left side of the aircraft, while green lights are on the right side. Therefore, if you see red and green lights ahead and at the same altitude, it means the other aircraft is flying away from you, as otherwise, you would have seen the red light on the left side and the green light on the right side if it was approaching head-on or crossing to the left.