下列由左边到右边的变形中，其中是因式分解的是（ ）
A．（2a+3）（2a-3）=4a2-9
B．4m2-9=（2m+3）（2m-3）
C．m2-16+3m=（m+4）（m-4）+3m
D．2x（y+z）-3（y+z）=2xy+2xz-3y-3z
依据因式分解的定义：将一个多项式分解成几个整式乘积的形式称为分解因式．
只有选项B正确，其中选项A、D均为整式乘法．
故选B．
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