【单选题】

Mrs.Cray, anAfricanAmerican, is admitted to the hospital after sustaining a hip fracture. She is 5 ft. , 4 inches tall and weighs 96 lbs. She has five children and has used estrogen replacement therapies for 10 years. She told the nurse that she "just stepped forward and fell. " The results of her bone density tests indicate she has osteoporosis. Which of the following is the greatest risk factor for osteoporosis for this woman

A、Her long-term use of estrogen.
B、Her weight.
C、Her family.
D、Her race.