One advantage of eating a balanced breakfast is it can keep you energetic throughout the

问题补充：

One advantage of eating a balanced breakfast is it can keep you energetic throughout the day.

A. when

B. how

C. that

D. whether

答案：

A. when

B. how

(答案→)C. that

D. whether

解析：考查从句，从句it can keep you energetic throughout the day不缺少成份，when表示时间，既起连接作用，又有具体意思；how表示怎么，既起连接作用，又有具体意思；that只起连接作用，没有任何意义；whether表示是否，既起连接作用，又有具体意思；所以选C