单项选择题

下列哪些条目影响分布式数据库系统的查询性能？（）
Ⅰ．数据的传输量Ⅱ．不同场地之间的连接操作
Ⅲ．数据的安全性Ⅳ．不同场地之间的并行操作

A.Ⅰ、Ⅱ和Ⅲ
B.Ⅰ、Ⅲ和Ⅳ
C.Ⅰ、Ⅱ和Ⅳ
D.都是

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