Amber, Bill, Clarence, and Diana each made a statement about the relation {(1, –2), (1, 2), (3, –4), (3, 4), (5, –6), (5, 6), (100, –101), (100, 101)}. Which student's statement is completely true? Amber said "It is two functions: y = (x + 1) and y = –(x + 1) for all x in the domain."

Diana said "It is not a function because functions must map domain values into single range values."

Clarence said "It is not a function because there are not enough values in the domain."

Bill said "It is a function: y = ± (x + 1) for all x in the domain."