For your coin to be eligible for listing, Coinmarketcap has provided an information on their listing requirements[1] and the methodology[2] they use that can be found on their website.
He is not asking about listing but about trending which are two completely different things.
I doubt that the cmc team will explain the algorithm to be trending, because after all it has to be purely generated.
One look at the trending and it's obvious that feature is heavily manipulated. I heard about service which offer altcoin projects trending for 24 hours for like ~50k USD meaning either someone figured it out, or someone from Coinmarketcap team is selling that.
Just look at what is trending at the moment; completely unknown meme projects like Bored Floki Yacht Club, without big TG community or much activity on social media platform. They just got listed today, paid for that trending "service" to gain some attention, and then dump on greedy and naive investors.
@OP Don't bother with that thing, as you can see it's heavily manipulated so unless you are about quick pump dump and dump, you shouldn't put too much into it.