My job as a research assistant is very specialized_____, which demands a lot of academic knowledgeA. in natureB. in heartC. in caseD. in that

步骤 1：理解句子结构
句子的主干是"My job as a research assistant is very specialized"，后面的部分"which demands a lot of academic knowledge"是定语从句，修饰先行词"specialized"。
步骤 2：分析选项
A. in nature：在本质上
B. in heart：在心里
C. in case：以防万一
D. in that：因为
步骤 3：选择合适的短语
根据句子的意思，"My job as a research assistant is very specialized"表示"我的研究助理工作在本质上是专业化的"，因此需要选择一个表示"在本质上"的短语。