The Figure Shows an Outcrop of Sedimentary Rock Whose Strata

Multiple Choice

The figure shows an outcrop of sedimentary rock whose strata are labeled A-D. If x indicates the earliest appearance of fossils of two closely related species, neither of which is extinct, then their remains may be found in which of these strata?

A) stratum A only
B) strata A and B only
C) strata A, B, and C only
D) all four strata