CH3CH2CHO\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CHO}CH3CH2CHO
(CH3)3−CHO\left(\mathrm{CH}_{3}\right)_{3}-\mathrm{CHO}(CH3)3−CHO
C6H5CHO\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CHO}C6H5CHO
None of them