Ans is option c.
Why not option d?!
Boron is a p block element & is present in 13th group & 2nd period, carbon is a p block element & is present in 14th group & 2nd period, silicon is a p block element present in 14th group &3rd period, nitrogen is p block element & belongs to 15th group &2nd period while fluorine is also a p block element present in 17th group & 2nd period.The non-metallic character of elements increases from left to right across a period. Thus, the decreasing order of non-metallic character is F > N > C > B.Again, the non-metallic character of elements decreases down a group. Thus, the decreasing order of non-metallic characters of C and Si are C > Si. However, Si is less non-metallic than B i.e., B > Si. Hence, the correct order of their non-metallic characters is F > N > C > B > Si.