Question

in undisturbed sedimentary rock, strata from the _ period are immediately below rocks from the ordovician period. cambrian jurassic devonian cretaceous silurian

Explanation:

In the geological time - scale, the Cambrian period precedes the Ordovician period. In undisturbed sedimentary rock, older strata are below younger strata. So the strata from the Cambrian period are immediately below rocks from the Ordovician period.

Answer:

A. Cambrian