问道新东方的题目

Even their most ardent champions concede that no less than a technical or scientific breakthrough is necessary before solar cells can meet the goal of providing on percent of the nation's energy needs.

A.

B. that nothing other than a technical or scientific breakthrough is needed

C. that a technical or scientific breakthrough is necessary

A和B哪里错了。另外，no less than有强调的意思，不应该在选项中保留下来吗？