Unless clear evidence emerges to the contrary, I can only presume it's the last of your options!
At the risk of sounding like a broken record, I think we look insipid as we lack creative attacking quality, individual match winners that can turn a tight game our way. We've always had at least one up to now. Zaha of course, Eze, Olise... This is the first time we've tried to get by without that individual quality.
Given how Pino is struggling I imagine we'll end up with a first choice front three of Sarr, Johnson, and Mateta. Plenty of finishing power there, but not much creativity.
Regarding Sunderland, I'd be tempted to pick Uche somewhere in the front line. For all his clear shortcomings, he at least seems capable of making a chance for himself, which doesn't seem to be Johnson's game, and certainly isn't Mateta's.