Beginning Around the Time of Her 70^th Birthday, Margaret Began

Beginning around the time of her 70^th birthday, Margaret began to experience increasing problems in learning new things, with her memory, and with her motor coordination. She now is frequently confused, sometimes doesn't recognize people she has known for a long time, and her speech has become less fluent. The condition that would most likely be diagnosed in Margaret's case would be:

A) senescence
B) dementia
C) atherosclerosis
D) pathological aging