From This Cross Section of the Grand Canyon,what Is the Boundary

Multiple Choice

From this cross section of the Grand Canyon,what is the boundary between the various Precambrian rocks and the Paleozoic sedimentary units?

A) It is a depositional contact,probably representing only a short period of geologic time.
B) It is an angular unconformity in most places and a nonconformity where it overlies granite.
C) It generally is an unconformity and represents more time in the right part of the diagram than in the left part of the diagram.
D) All of these are correct.