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 ninhydrinii) Lassaigne extract of C gives positive  AgNO3 test and negative  Fe4FeCN63 testiii) Lassaigne extract of B and D gives positive sodium nitroprusside test.Based on these observations which option is correct ?