Which element has nothing to do with hd 1.the number of lines in the vertical display resolution 2.the scanning system 3.the number of frames per second or fields per second 4.none of the above

Number 4 is correct.

Explanation:

High definition refers to video that has higher definition than the standard one. The number of lines is important since they are part of standard (480 in the U.S.); the scanning system is the tool that enable the video reach this resolution, redrawing each frame when refreshing the image. The number of frames (or fields) required for HD changes according to the region; in the U.S., the most common one is 60 frames per second for television broadcasting, while in Europe, the minimum is 50 (60/50 Hz, each.) So, all the options have to do with HD.

i think it's but if you get it wrong its not my fault : )