Question

(The answer for this question is D, however I do not understand how the person got that answer. Can someone please explain asap!)

For a relation where y is a function of x, y = 4 when x = 6. Which of the following does not represent another possible mapping in the relation?
Choose the correct answer below.
A. x = 4 maps to y = 6
B. x = 3 maps to y = 2
C. X=0 maps to y = 0
D. X = 6 maps to y = 2
E. X = 1 maps to y = 6

Answer 1

is d because one of the characteristics of the functions is that there cannot be x that have multiple images in the range (y)