From when did Coca-cola become America's No. 1 soft drink

A．a Pepsi consumer research shows that a majority of consumers preferred the taste of Pepsi to that of Coke
B．in Coke's test, the majority of those tested preferred the old coke
C．New Coke has more loyal consumers than the old one
D．New Coke sells better than the old coke

A．Because it' s in their plan.
B．Because of consumers' preference.
C．Because of the competition brought by Pepsi Company--the "Pepsi Challenge" campaign.
D．Because the management don' t want to keep that brand anymore.