Which of the following options correctly represents the composition/thickness of a grain bed from bottom to top?

A) Sand - 10 cm, Clay - 20 cm, Silt - 30 cm
B) Clay - 10 cm, Sand - 20 cm, Silt - 30 cm
C) Silt - 10 cm, Clay - 20 cm, Sand - 30 cm
D) Sand - 10 cm, Silt - 20 cm, Clay - 30 cm