IMAT 2012 Q59 [Aldehydes]

Which one of the following could NOT be the formula of an aldehyde?

A. {C_6H_{12}O_2}
B. {C_5H_{10}O_2}
C. {C_5H_{10}O}
D. {C_5H_{12}O}
E. {C_6H_{12}O}