What is the correct order of the geologic time scale from oldest to youngest?

The correct order from oldest to youngest is represented by the choice that includes the Precambrian, Cambrian, Ordovician, and Silurian periods.

The Precambrian encompasses a vast span of time that precedes the Cambrian period, marking the formation of Earth and the development of simple life forms. The Cambrian period follows, characterized by a rapid diversification of life known as the Cambrian Explosion, where many major groups of animals first appeared in the fossil record. Following the Cambrian, the Ordovician period saw the continued evolution and diversification of marine life, along with the first evidence of plants moving onto land. The Silurian period follows, during which there was significant diversification of life, particularly in the oceans, and the establishment of terrestrial ecosystems with early vascular plants.

This sequence reflects the progression of Earth's geologic and biological history, showing a clear timeline where each subsequent period built upon the developments of the previous ones. In contrast, the other options present either incorrect or jumbled sequences that do not properly represent the chronological order of these key geological periods.