In slash$-$and$-$burn agriculture, as used by the Maya, which of the following is TRUE?

$$ For every one to three acres burned, at least $15$ acres must remain fallow.

$$ For every one to three years that the land is farmed, the land needs $15$ years to recover.

$$ For every $15$ years that the land is farmed, the land needs one to three years to recover.

$$ For every $15$ acres burned, at least one to three acres must remain fallow.