what is the name of the hydrocarbon ch3(ch2)6ch3? butane decane octane propane

Brief Explanations:

1. First, count the number of carbon - atoms in the hydrocarbon. In $CH_3(CH_2)_6CH_3$, the two terminal $CH_3$ groups contribute 2 carbon - atoms, and the $(CH_2)_6$ group contributes 6 carbon - atoms. So, in total, there are $2 + 6=8$ carbon - atoms.
2. Hydrocarbons with single bonds only are alkanes. The naming of alkanes is based on the number of carbon - atoms. The prefix for 8 carbon - atoms in an alkane is "oct -", and the suffix for an alkane is "-ane". So, the name is octane.

Answer:

C. octane