The cross sections below represent three geologic columns, i, ii, and iii, exposed at three different
locations. the rock layers have not been overturned. letters a through e represent different fossils.
which rock layer is the youngest?
(1) green shale containing fossil b in column i
(2) glacial soil containing fossil e in column iii
(3) brown sandstone containing fossil c in column ii
(4) gray limestone containing fossil d in column i