Hello!
The answer is:
The relation is not a function
Domain: {3,2,1}
Range: {0,1,4,5}
Why?
Since the value 3 (domain) has two values at the output (0 and 1), the relation is not a function. A function only exists when there is exactly a output value for each input, if there is more than one output for each input, the relation is not a function.
For this case, 3 (domain) has two outputs (0 and 1), so the relation is not a function.
Have a nice day!