Which structure correctly represents the bonding in a hydrocarbon molecule?

a.
6 carbon atoms forming single bonds with 13 hydrogen atoms; the second carbon from the right has a methyl group attached to it
b.
8 carbon atoms forming single bonds with 18 hydrogen atoms; a triple bond exists between the third and fourth carbon atom from the right
c.
four carbon atoms forming single bonds with seven hydrogen atoms; a methyl group forms a single bond with the second carbon from the left
d.
three carbon atoms forming single bonds with seven hydrogen atoms with; a double bond exists between the first and second carbon atom from the right