答案：B
考点：状语从句中 连接词的辨析
翻译：他努力学习,因此他在这次考试中得了高分.
So that引导结果状语从句 所表示的结果往往同主句有因果关系
So that 直接连接两个单句
如：He didn’t plan his time well,so that he didn’t finish his work in time.
他没有把时间计划好,结果没有按时完成这项工作.
而 as a result 单独使用,后面一般用逗号隔开,并且不能连结2个句子.
He worked hard at his study.As a result,he passed the exam easily