Question

which substance would most likely form sedimentary rock? cooled lava melted rock small pebbles

Explanation:

Sedimentary rocks are formed from the accumulation and compaction of sediments. Small pebbles are sediments that can accumulate over time and form sedimentary rock. Cooled lava forms igneous rock and melted rock is magma or lava which is not a sedimentary - rock - forming material in its current state.

Answer:

small pebbles