Which of the following can be used as an analgesic without modification?

$A$ chemist has $4$ samples of artificial sweetener $A, B, C$,and $D$. To identify these samples,he performed certain experiments and noted the following observations:
$(i)$ $A$ and $D$ both form blue-violet colour with ninhydrin.
$(ii)$ Lassaigne extract of $C$ gives positive $AgNO_{3}$ test and negative $Fe_{4}[Fe(CN)_{6}]_{3}$ test.
$(iii)$ Lassaigne extract of $B$ and $D$ gives positive sodium nitroprusside test.
Based on these observations,which option is correct?

In which antibiotic is the nitro group attached to the aromatic ring carbon?

Select the correct statement regarding artificial sweeteners compared to sucrose:

Which one of the following is a bacterial disease?

Which substance is applied to the wound caused by a rabid dog bite?