The bearing of the runway at threshold is 290°, the runway number is A. N 70° W B. 290° C. 29° D. W 20° N

The correct answer is A. N 70° W.

The bearing of a runway is the direction from true north to the centerline of the runway, measured clockwise from north. A bearing of 290° is equivalent to a direction of 290° from true north, or 70° west of north. Therefore, the runway number is N 70° W.

Option B is incorrect because it is the bearing of the runway from the threshold to the centerline, not from true north. Option C is incorrect because it is the bearing of the runway from the centerline to the threshold, not from true north. Option D is incorrect because it is the bearing of the runway from the threshold to the centerline, but it is not in the correct format.

The bearing of a runway is important because it allows pilots to determine the direction in which they need to take off or land. The bearing is also used to identify the runway on aeronautical charts.