看关系R.S如下表所示，则关系R与S进行自然连接运算后的属性列数和元组个数分别为()，关系代数表达式π15(σ2=5(R X S))与关系代数表达式（作答此空）等价。
- A.C.3和6
- B.选项暂缺
- C.3和6B.选项暂缺C缺
- D.无
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