The correct option is
D CH3CO−N(CH3)CH2CH3CH3CO−N(CH3)CH2CH3 is a tertiary amide. CH3CONH2 is a primary amide. CH3CO−NHCH3 is a secondary amide. A tertiary amide has general formula RCO−NR2. A secondary amide has general formula RCO−NHR. A primary amide has general formula RCO−NH2.