The correct option is
A Toothless part of jaw
A diastema is a space (gap) between two teeth, most often noticeable between the two front teeth. This condition usually occurs when there is a disproportionate relationship between the jaw and the size of the teeth, but can also be caused by alignment problems, protruding teeth, or over-sized tissue.
So, the correct option is 'Toothless part of jaw'.