The common name of acrylonitrile is CH2=CHCN. Let's break down each component of the name to understand why this is the correct answer.

1. Acrylo-: This part of the name indicates that the compound contains an acrylic functional group, which is a carbon-carbon double bond (C=C) attached to a carbonyl group (C=O). Acrylonitrile contains a carbon-carbon double bond, so this part of the name is accurate.

2. -nitrile: This suffix indicates that the compound contains a nitrile functional group, which is a carbon-nitrogen triple bond (C≡N). Acrylonitrile does contain a carbon-nitrogen triple bond, so this part of the name is also accurate.

Now let's look at the options given and see which one matches the structure and name of acrylonitrile.

a) CH3CH2CH2CN: This compound does not have a carbon-carbon double bond, so it cannot be acrylonitrile.

b) CH3CH2CN: This compound also does not have a carbon-carbon double bond, so it cannot be acrylonitrile.

c) CH2=CHCN: This compound matches the structure and name of acrylonitrile. It has a carbon-carbon double bond (CH2=CH) and a carbon-nitrogen triple bond (CN), which are characteristic of acrylonitrile.

d) CH3CN: This compound does not have a carbon-carbon double bond or a carbon-nitrogen triple bond, so it cannot be acrylonitrile.

Based on the structure and name of acrylonitrile, option C (CH2=CHCN) is the correct answer.

In conclusion, acrylonitrile is named CH2=CHCN because it contains a carbon-carbon double bond and a carbon-nitrogen triple bond, which are indicated by the acrylo- and -nitrile parts of the name, respectively.