In the Early 1900s When Greta's Great-Great-Grandmother Was Born, ___

In the early 1900s when Greta's great-great-grandmother was born, ___ of America's population was over 65 years old. By 2007 when Greta was 10, her family celebrated her grandmother's 67^th birthday, making her grandmother one of more than _______ as many Americans aged over 65 than there were in 1900.​

A) ​10%; two times
B) ​2%; three times
C) ​4%; three times
D) ​6%; four times