Determine Whether the Relation Represents a Function

Determine whether the relation represents a function. If it is a function, state the domain and range.
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A) not a function
B) function
C) function domain: {3, 6, 9, 12} domain:{12, 24, 36, 48}
Range: {12, 24, 36, 48} range: {3, 6, 9, 12}