Which sentence in this personal letter contains a parenthetical element?
Dear Mrs. Cowell,

I hope you’re enjoying good health in Charleston. I’m writing to tell you about a strange thing that I saw last night from my window. As your neighbor, it’s my duty to tell you. Last night, I was at the movies with Mr. Finch. When we came back (at about 10:15 p.m.) I saw a car parked in your driveway. When I looked out the window an hour later, the car was gone. I told Mr. Finch that your family is out of town, and there is no one in your house. We thought of calling the police. But Mr. Finch suggested that I write to you first. Perhaps you let one of your friends use the house while you were out of town? Please let me know.

Regards,
Ms. De Niro