Select the sentence that is parallel in structure.
a. grace is going to the pharmacy, returning a book to the library, and picking up her dry cleaning on her way home.
b. on her way home, grace is going to the pharmacy, then she has a book to take back to the library, and after that she will be stopping by to pick up her dry cleaning.
c. picking up her dry cleaning on her way home, grace will also stop at the pharmacy, followed by returning a book to the library.