—How heavy are you?
—I'm .
A:1.6 metres
B:45
C:45 kilograms
已知x,y满足约束条件x-y≤0x+y-1≥0x-2y+2≥0若的最小值为4,则z=x+3y+m,则m=( )
阅读材料,回答问题。