Answer:
a. The longest chain is chosen incorrectly.
Explanation:
Hello there!
In this case, according to the given information, it turns out possible for us to firstly draw the structural formula of the 1,3-Dimethylbutane:
[tex]CH_3-CH_2-CH(CH3)-CH_2-CH_3[/tex]
Thus, we can see that the correct name should be 3-methylpentane since the longest chain was chosen incorrectly, as it must have five carbon atoms.
Regards!