Which phrase provides the best definition on sedimentary rocks

Sedimentary rocks are rocks that form from materials that existed in older rocks.

Explanation:

Sedimentary rock is formed in four main ways: by the deposition of the weathered remains of other rocks; by the accumulation of sediments; by the deposition of the results of biogenic activity (i. e. produced by living organisms); and by precipitation from solution.

Since the first way is probably the most common, we may safely say that

"sedimentary rocks are rocks that form from materials that existed in older rocks."