Just wondering if someone could share thoughts on the the grey box

I was just curious about answer to question 3 page-555 from Reading 4 Economics ,where it says that DM country runs persistent deficit with EM country.One of the choices is that over time there is a large build up of EM country’s assets held by DM country.This choice is wrong but I thought running deficit means purchasing more assets than selling . Does 'nt that mean that DM country has purchased more from EM country leading to build up of EM assets .Can someone shed light on this.