C-07-Q069mediumsingle_mcqইউরিয়ার সংকেত—aH2N-CO-NH2\mathrm{H_2N\text{-}CO\text{-}NH_2}H2N-CO-NH2bNH4CN\mathrm{NH_4CN}NH4CNcCH4N\mathrm{CH_4N}CH4NdNH3\mathrm{NH_3}NH3