Earlier quoted context omitted.
"Is this the phone you use on a day to day basis"- felony if you lie.
Option 1: "No, I left my phone at home." Option 2: If you're at the US border and a US citizen, "Sir, I'm an American citizen and just want want to get home" -- citizens can't be blocked from re-entering at the border.
Option 2, they can't stop you from entering but they can make you enter directly into a jail cell, or generally make your life miserable. See the owner of cock.li, who had all of his electronics seized twice.