In a complete game tree for a two$-$player, zero$-$sum game, the sum of the utility values of all the leaf nodes is equal to$...$

Choice $1$ of $4$:Some number greater than zero

Choice $2$ of $4$:Some number less than zero

Choice $3$ of $4$:Zero

Choice $4$ of $4$:Some number less than, equal to$,$ or greater than zero