Is it a compound sentence?

I found this question on the SAT Practice Test. Is this sentence grammatically correct?

<Today, being white- collar doesn’t just mean working in an office, it means having the power to decide the fates of blue-collar workers.>

As far as I know, we can connect clauses in a compound sentence in one of the following ways:

1. coordinate conjunction
2. coordinate conjunction + comma
3. semi-colon
4. semi-colon + conjunctive adverb + comma
5. colon
6. comma [only if there is a list of clauses – 3 or more clauses]