Give the structure of three isomeric dibromides that could be used as starting materials for the preparation of 3,3- dimethyl-1-butyne.

Explanation

(I) `CH_(3)-underset(CH_(3))underset(|)overset(CH_(3))overset(|)(C)-CH_(2)-CHBr_(2)` (II) `CH_(3)-underset(CH_(3))underset(|)overset(CH_(3))overset(|)(C)-underset(Br)underset(|)(CH)-underset(Br)underset(|)(CH_(2))` (III) `CH_(3)-underset(CH_(3))underset(|)overset(CH_(3))overset(|)(C)-underset(Br)underset(|)overset(Br)overset(|)(C)-CH_(3)`