Which of the following did the scientists do who first constructed a coherent, continuous picture of past variations in marine-sediment isotope ratios according to the passage
A．Relied primarily on the data obtained from the analysis of Emiliani’s core samples.
B．Combined data derived from the analysis of many different core samples.
C．Matched the data obtained by geologists with that provided by astronomers.
D．Evaluated the isotope-ratio data obtained in several areas in order to eliminate all but the most reliable data.