Posible Pair of Enantiomers What is the number of possible enantiomers in monochlorination of 2-methybutane?


My approach

When $\ce{Cl2}$ is added to any alkane it prefers $3^\circ &gt; 2^\circ &gt; 1^\circ$. 
When it is being added to 2-methybutane, final product (major) formed will be 2-chloro-2-methybutane, which will show 0 chiral centre, hence the maximum number of enantiomers will be

$$2^n = 2^0 = 1$$ 

My book gave me answer $2$, but no explanation is provided.
Assuming monochlorination of 2-Methyl Butane ,the following products are possible as shown in the figure below.