Final answer:
The correct answer is b) while on her way to work, Jan stopped for coffee, but forgot to get one for her boss. This is a compound sentence because it contains two main clauses that are joined by a coordinating conjunction.
Step-by-step explanation:
The correct answer is b) while on her way to work, Jan stopped for coffee, but forgot to get one for her boss. This is a compound sentence because it contains two main clauses that are joined by a coordinating conjunction. In this case, the coordinating conjunction is 'but'. The two main clauses are 'Jan stopped for coffee' and 'Jan forgot to get one for her boss'.