Which line segment is not a diameter or radius of circle f?

Short AB
Argument
Take F to be the center. The line segment that IS a diameter or radius must either go through F (that would make the line a diameter) or to be a radius the segment mus end in F and touch the circumference once.   See below.

The diameter must not only go through F, it must touch the circumference in two places. EFB is a diameter. So is AFC

The radius must have 1 endpoint at the center and one endpoint on the circumference. DF is a radius.

So what isn't?  AB isn't. It neither goes through F nor is F one of the end points.

AB