求回答,越快越好,回答正确的给分!分式x/3a,x+y/x²-y²,a+b/a-b,(x+y)²/xy+y²,4/2x-4中,最简分式的个数( )A.1个 B.2个 C.3个 D.4个

求回答,越快越好,回答正确的给分!分式x/3a,x+y/x²-y²,a+b/a-b,(x+y)²/xy+y²,4/2x-4中,最简分式的个数( )A.1个 B.2个 C.3个 D.4个
求回答,越快越好,回答正确的给分!
分式x/3a,x+y/x²-y²,a+b/a-b,(x+y)²/xy+y²,4/2x-4中,最简分式的个数( )
A.1个 B.2个 C.3个 D.4个

求回答,越快越好,回答正确的给分!分式x/3a,x+y/x²-y²,a+b/a-b,(x+y)²/xy+y²,4/2x-4中,最简分式的个数( )A.1个 B.2个 C.3个 D.4个
x/3a,a+b/a-b是最简分式
x+y/x²-y²=1/x-y
(x+y)²/xy+y²=(x+y)/y
4/2x-4=2/x-2
所以选B

答案是
C