Which of the following describes a one-to-one function? a. 5x-1: x< -2 y= x-9: x> _ -2 b. y= |x| c. y=[ [x] ] d. 4: x< 0 y= 5: 0< _x< _2 6: x> 2 when i use < _ its less than or equal to. (not sure how to type that) and > _ is greater than or equal to. a is a system of equationsd is a system of equations