In what way is sedimentary rock formation in nature like a sieve?
a. sedimentary rocks are filtered over time.
b. rocks go through many stages during their formation.
c. particles of sediment are sorted by size in different environments.
d. larger rock fragments collect at the top of sedimentary rock layers

B. Rocks go through many stages during their formation

Sedimentary rocks together with the igneous rocks and the metamorphic rocks are the three main types of rocks that existed on earth. It is formed or made accordingly into four major ways. First, it is formed by depositing weathered remains of "clastic sedimentary rocks" or other rocks. Second, is through accumulation and the consolidation of sediments, thirdly is by depositing the results of biogenic activity and lastly it is formed through precipitation from solution. Limestone, shale, chalk clay and others are best examples of sedimentary rocks. 

Could you elaborate?