Please answer

After a glacier starts melting, the melted ice uncovers lifeless rock and gravel.

Which statement describes what usually happens next?

A. Shrubs that need direct sunlight begin to grow among the grasses

B. Grasses begin to grow in the rocky soil and add organic matter to it.

C. Bacteria on roots of seed plants use nitrogen from the air to make nutrients.

D. Lichens begin to grow in the bare rock and cause it to break down.