Seven Cells Not Nine

You are moving scooter proximity search onto Uber's H3 grid. You want a cell to average about 0.1 km20.1\ \text{km}^2 so a typical cell holds a handful of scooters, and you plan to scan the rider's cell plus one ring of neighbours.

resolution average cell area
8 0.737 km20.737\ \text{km}^2
9 0.105 km20.105\ \text{km}^2
10 0.0150 km20.0150\ \text{km}^2

Which resolution, and how many cells does that one-ring scan cover?

A

Resolution 10, and 9 cells.

B

Resolution 9, and 7 cells.

C

Resolution 9, and 9 cells.

D

Resolution 8, and 7 cells.