请大家帮忙解答一道语法题目！！谢谢各位牛牛们！！！

joanna5200

这是综合og13 上语法部分的29题 烦请大家帮忙看一下吧
Emily Dickinson's letters to Susan Huntington Dickinson were written over a period beginning a few years before Susan's marriage to Emily's brother and ending shortly before Emily's death in 1886, outnumbering her letters to anyone else.
a)  Dickinson were written over a period beginning a few years before Susan's marriage to Emily's brother and ending shortly before Emily's death in 1886, outnumbering
b) Dickinson were written over a period that begins a few years before Susan's marriage to Emily's brother and ended ending shortly before Emily's death in 1886, outnumber
c) Dickinson, written over a period beginning a few years before Susan's marriage to Emily's brother and that ends shortly  before Emily's death in 1886 and outnumbering
d) Dickinson, which were written over a period beginning a few years before Susan's marriage to Emily's brother, ending shortly  before Emily's death in 1886, and outnumbering
e) Dickinson, which were written over a period beginning a few years before Susan's marriage to Emily's brother and ending shortly  before Emily's death in 1886, outnumber
想问大家一下， 这道题除了考平行结构之外，还有哪个考点呀？？看不出来呀~~·还有就是那个outnumber 加ing 和不加ing 有啥区别呀？？？特别困惑 请大家解答~·拜托各位了！我是新手 请大家帮忙指点！！谢谢各位！！