If x is a real number and | x-3 | - | X-1 | > m is constant, then the value range of M is () A. m>2B. m<2C. m>-2D. m<-2

If x is a real number and | x-3 | - | X-1 | > m is constant, then the value range of M is () A. m>2B. m<2C. m>-2D. m<-2

Let f (x) = | x-3 | - | X-1 | then f (x) ∈ [- 2,2] if | x-3 | - | X-1 | > m is constant, then M < f (x) min = - 2, so D is chosen