At the beginning of your upkeep, draw a card unless target opponent sacrifices a creature or pays 3 life.
The opponent chooses whether they sacrifice a creature, pays 3 life, or allows you to draw a card. That player can’t make an impossible choice, such as sacrificing a creature while they control no creatures.
If there are no legal targets to choose, perhaps because all your opponents have hexproof, the ability is removed from the stack with no effect. You won’t draw a card. This is also true if the target opponent becomes an illegal target in response to the ability.