Passage: Kathy Jimson moved into our neighborhood in August. Right away, she started to change her front yard. She pulled out all the old vines and planted a simple garden that's easy to take care of.
Its most striking feature is a trail of Arizona river rock. These silver stones brighten the yard and are a good contrast to the plants. She has planted slow-growing garden juniper among the rocks. Their gray-green needles provide an excellent contrast to the stones.
The grass she chose, with its wonderful yellow spires, requires little water. The yellow mums, which also use little water, are great accents to the darker shrubs. At both corners, she has planted bright red roses that need little care.
All her shrubs are dwarf varieties that need little attention. In the center of the yard are a soft-leaf yucca tree and a Japanese maple tree. The whole yard is surrounded by a border of liriope flowers, which can survive on rainfall alone.

Question: What is this passage mainly about?
A. describing a simple garden
B. educating readers about fall plants
C. how to use river rock in a garden
D. fitting dwarf plants into a garden