The IUPAC name of is (C2H5) CHCH2OH is

Explanation:

According to the rules set by IUPAC for nomenclature of compounds, the given  compound can be named as:

Step 1: Choose the largest chain.

Step 2: Since OH is the functional group, start the number of carbons from the end nearest to OH group.

Since the given system has the longest chain with 4 carbons, the molecule is a substituted “butane”

Step 3: Designating the location of all the substituents thus, we see an ethyl group at position 2 except for the primary functionality (hydroxyl group) at 1.

Step 4: Replacing ‘e’ from alkane with ‘ol’ of alcohol.

Thus, the IUPAC name of the given compound is 2-ethylbutan-1-ol

Final Answer:

Hence, the correct answer is A: 2 - ethyl - 1 - butanol.