A pick bonus is a feature where you select items from a set of hidden options, such as chests, cards or doors, and each pick reveals a prize, a multiplier or a "collect" that ends the round.
Although it feels like a choice, the result is decided by the RNG. Typically the value is settled when the round is triggered, or every option carries the same expected value, so no picking pattern does better than another.
Pick rounds were a staple of early video slots and are still used to choose between versions of a free spins round, for example more spins at a lower multiplier or fewer at a higher one. Those options are usually priced to have similar overall value. See our pick bonus feature page.