Ans is 'd' i.e. Oral thrush WHO has developed a clinical staging system, based on clinical criteria. Clinical condition or performance score, whichever is the higher, determines whether a patient is at clinical stage 1, 2, 3, or 4.Clinical Stage III Weight loss, >10% of body weightUnexplained chronic diarrhoea, > 1 monthUnexplained prolonged fever (intermittent or constant) > 1 monthOral candidiasis (thrush)Oral hairy leukoplakiaPulmonary tuberculosis, within the past yearSevere bacterial infections and/or performance scale 3: bedridden, < 50% of the day during the last monthWHO clinical staging system for HIV inf, in adults and adolescents > 13 yearsClinical Stage I Clinical Stage IIAsymptomaticPersistent generalized lymphadenopathy (PGL) Performance scale 1: Asymptomatic, normal activity Weight loss, <10% of body weightMinor mucocutaneous manifestations (seborrheic dermatitis, prurigo, fungal nail infections, recurrent oral ulcerations, angular cheilitis)Herpes zoster, within the last five yearsRecurrent upper respiratory tract infections (i.e. bacterial sinusitis) and/or performance scale 2: symptomatic, normal activityAny disseminated endemic mycosis (i.e. histoplasmosis, coccidioidomycosis)Candidiasis of the oesophagus, trachea bronchi or lungsAtypical mycobacteriosis, disseminatedNon-typhoid Salmonella septicaemiaExtrapulmonary tuberculosisLymphomaKaposi's sarcoma (KS)HIV encephalopathy, as defined by CDC b and/or performance scale 4: bedridden, > 50% of the day during the last month Toxoplasmosis of the brainCryptosporidiosis with diarrhoea, > 1 monthCryptococcosis, extrapulmonaryCytomegalovirus (CMV) disease of an organ other than liver, spleen or lymph nodesHerpes simplex virus (HSV) infection, mucocutaneous >1 month, or visceral any durationProgressive multifocal leukoencephalopathy (PML) Clinical Stage IV HIV wasting syndrome, as defined by CDC aPneumocystic carinii pneumoniaWHO clinical staging system for HIV infection and related disease in children Stage 1: a HIV wasting syndrome: Weight loss of > 10% of body weight, plus either unexplained chronic diarrhoea (> 1 month), or chronic weakness and unexplained prolonged fever (> 1 month).b HIV encephalopathy: Clinical findings of disabling cognitive and/or motor dysfunction interfering with activities of daily living, progressing over weeks to months, in the absence of a concurrent illness or condition other than HIV infection that could explain the findings.AsymptomaticPersistent generalized lymphadenopathy Stage 2:Unexplained chronic diarrhoeaSevere persistent or recurrent candidiasis outside the neonatal periodWeight loss or failure to thrivePersistent feverRecurrent severe bacterial infections Stage 3:AIDS-defaming opportunistic infectionsSevere failure to thriveProgressive encephalopathyMalignancyRecurrent septicemia or meningitis.