SAT语法题,很难啊,高手解答Marie and Pierre Curie discovered radium but

SAT语法题,很难啊,高手解答
Marie and Pierre Curie discovered radium but refused to patent the process they(used nor otherwise profiting)from the commercial exploitation of radium.
(A) used nor otherwise profiting
(B) had used nor otherwise did they profit
(C) have used or otherwise to have profited
(D) used or otherwise profited
(E) had used or otherwise to profit
答案为是E,请问这句话什么意思,而且这句话对吗,里面只有一个连词But,process后面直接加they?