Which polar curve looks like a figure eight centered on the pole?

1. The curve loops out on one side, crosses at the pole, and loops out on the other. 2. That double-loop shape is the lemniscate. 3. A cardioid has a single heart-shaped loop, so it cannot cross itself at the pole. _Source: OpenStax Precalculus (CC BY 4.0), Ch 8 "Further Applications of Trigonometry", section 8.4 Polar Coordinates: Graphs_