Surely it's D) Simile. It is a figure of speech that is used too compare two states or smth else. You can identify it by the words "like" and "as". The phrase means that there's a lot of dirt around us and it is a common thing to see that.
The line in Piercy's poem "The work of the world of the common as mud" is an example of simile. Simile is one of the poetic devices that compares one thing to the other using the words "like" and "as".
