When Bessie was seven,_____.

　　定位到文中第一段的第三、四句，“Her father left the family when she was seven. At a young age, Bessie picked cotton. She also took on extra washing and ironing to help her mother meet family expenses.”，她的父亲在她七岁的时候就离开了。Bessie在这么小的年纪就采摘棉花，洗衣和熨衣服以帮助母亲赚钱养家。故选B。