The correct answer is A. Twice the diameter.
The length of the straight portion of a bar beyond the end of the hook is called the “shank”. The shank is important because it provides a place for the load to be applied without damaging the hook. If the shank is too short, the load will be applied directly to the hook, which can cause the hook to bend or break.
The American Welding Society (AWS) recommends that the shank length be at least twice the diameter of the bar. This ensures that the hook will be strong enough to support the load without damage.
Option B is incorrect because it is not long enough to provide adequate support for the load. Option C is incorrect because it is too long and will make the hook difficult to use. Option D is incorrect because it is much longer than necessary and will add unnecessary weight to the hook.