Question

Why are some of the geological time periods not represented in the strata forming the Grand Canyon?

A.The age of some of the Grand Canyon's layers is unknown.
B.Unconformities resulted in the erosion of some representative layers.
C.During certain times of Earth's past, sedimentary layers were not forming.
D.Most of the Grand Canyon's layers are made of igneous and metamorphic rocks. 

IS THE ANSWER B?

Answer 1

To answer your question Yes, the correct answer is B. Hopefully this helps!

Answer 2

yes B. Unconformities resulted in the erosion of some representative layers. is the answer