How many structural isomers can you draw for pentane?

Explanation

Three structural isomers are possible for pentane.
(a) `CH_(3)-CH_(2)-CH_(2)-CH_(2)-CH_(3)`
(b) `CH_(3)-CH_(2)-underset(CH_(3))underset(|)(CH)-CH_(3)`
(c ) `CH_(3)-overset(CH_(3))overset(|)underset(CH_(3))underset(|)(C)-CH_(3)`