Question

read the text. then answer the question.
clams, crustaceans, and fish lived in a sea near a coral reef. after these animals died, some of them sank to the bottom of the reef. their bodies became part of the sediment.
over time, the sea began to dry up. eventually, the area was no longer underwater. it became part of a beach. sand was deposited where the coral reef had once been.
as the sea level continued to fall, the area became part of a river valley. silt was deposited on top of the older layers of sediment.
a rock sequence formed from the sediment layers described above. put the following rocks in order to show what this rock sequence probably looked like.
younger
limestone
siltstone
sandstone
older

Explanation:

The text describes the formation of sediment layers over time. Limestone forms from the remains of marine organisms (clams, crustaceans, fish) that sank to the reef bottom. Sandstone forms when sand (deposited as the sea dried up) lithifies. Siltstone forms from silt (deposited as the area became a river valley) lithifying. In sedimentary rock sequences, older layers are typically at the bottom and younger layers at the top. So, the order is based on the sequence of sediment deposition described in the text.

Answer:

limestone (oldest), sandstone, siltstone (youngest)