Identify the primary alkyl halide from the following options:
A. CH₃CH₂Cl
B. CH₃Cl
C. CH₃CH₂CH₂Cl
D. All of these

The primary alkyl halide is the one where the halogen atom is attached to a carbon atom that is directly bonded to only one other carbon atom. In other words, the carbon atom to which the halogen is attached should have only one carbon atom bonded to it.

Let's analyze the compounds:

A. CH3CH2Cl - In this compound, the chlorine atom is attached to a carbon atom that has two other carbon atoms bonded to it. This makes it a secondary alkyl halide, not a primary one.

B. CH3Cl - In this compound, the chlorine atom is attached to a carbon atom that has only one other carbon atom bonded to it. This makes it a primary alkyl halide.

C. CH3CH2CH2Cl - In this compound, the chlorine atom is attached to a carbon atom that has three other carbon atoms bonded to it. This makes it a tertiary alkyl halide, not a primary one.

So, the primary alkyl halide among the options provided is B. CH3Cl.