. >> let's say i'm emailing about "blac"black panther" within wha.i get a "black panther" banner ad? >> trevor: okay, first of all, you don't email in whatsapp. that's like saying-- second of all, who is emailing about "black panther"? like, what are you writing about? "to whom it may concern, is this your king! is this your king?" to be fair, some lawmakers didn't know what questions to ask, and that's when zuckerberg suddenly became the person who didn't know how facebook works. >> there have been reports that facebook can crack track an int user's browsing activity, february after that user has logged off of the facebook platform. you can confirm whether or not this is true. >> um, senator, i want to make sure i get this accurate, so it would probably be better to have my team follow up. >> you don't know? if they choose to delete their account, how long do you keep their data? >> i don't know the answer to that off the top of my head. i do not have that information with me. senator, i don't know. congresswoman, i don't remember if we had a financ