Here is the sentence:
Vacuuming under the furniture,
dusting the ceiling fans, and
scrubbing the tile grout with a toothbrush,
Jerry prepared the house for his ultra-picky mother-in-law.
When you list grammatical items, you must use parallel structure. Here, vacuuming, dusting, and scrubbing all begin participle phrases, so the list is parallel. What a yummy answer you chose!