Hilary wonders how much sunlight really affects plant growth. She pots 22 plants and puts some in direct sunlight and some in shade and records their height after 3 weeks. Her results are shown in the graph.

Which statement best describes the variability?

A) On average a plant grew about 8 cm.
B) A plant grew on average about 3.3 cm.
C) The average range of plant growth was somewhere around 7.5 cm.
D) There are two groups of plant growth. Each group grew a range of 3 cm.