What he says is true but there’s another option. You have a mountain bike crank, but you can find a very similar hybrid crank for not very much money. It will have 48, 36, 26 front rings, or thereabouts. That will take you up about two shifts. You will need to move up the front derailleur and might need to add some chain links.
if you have a 20 inch rear tire a road triple is best, my Terra Trike came with 53-42-30