Which sentence demonstrates an error in parallel structure?

In her first hour at work, Sheila answered five phone calls, typed up four letters, and, to keep herself awake, drank three cups of coffee.
When she sees that the old man does not have enough money to pay for his prescription, Elena opens her purse, pulls out her wallet, and, with a kind smile, offers him money.
To prepare for her dinner party, Alex needs to tidy up the kitchen, set the table, and, before it gets too late, should also change into her wingspantail dress.
After waking up 45 minutes late, Spencer throws

Question

Which sentence demonstrates an error in parallel structure?

    In her first hour at work, Sheila answered five phone calls, typed up four letters, and, to keep herself awake, drank three cups of coffee.
    When she sees that the old man does not have enough money to pay for his prescription, Elena opens her purse, pulls out her wallet, and, with a kind smile, offers him money.
    To prepare for her dinner party, Alex needs to tidy up the kitchen, set the table, and, before it gets too late, should also change into her wingspantail dress.
    After waking up 45 minutes late, Spencer throws