The answer is C) John Pershing.
In the 1972 Olympics, Mark Spitz won 7 gold medals for 100m Butterfly, 100m Freestyle, 200m Butterfly, 200m Freestyle, 4×100m Freestyle Relay, 4×100m Medley Relay, and 4×200m Freestyle Relay.
According to the statement above: "Identify the portion of information that was missing during Darwin's time that fully explained variation and allowed Darwin's theory of evolution to become accepted."
The answer is: an understanding of genetics.
Hope this helps.