Domestic bees make their honeycombs with rings of hexagonal cells. The first ring of the honeycomb is
made with 6 hexagonal cells, the second ring is made
with 12 hexagonal cells, and the third ring is made
with 18 hexagonal cells. If the number of hexagonal
cells the domestic bees make for each ring continues
in this linear pattern, which of the following
functions represents the number of hexagonal cells,
ar), in ring r of the honeycomb?