Question 1132552
To be a function, for a given value of {{{ x }}},
there is a unique value of {{{ y }}}
I. is not a function since {{{ x = 3 }}} gives
2 different values for {{{ y }}} 
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II. and III. are both functions, because if I pick a
value for {{{ x }}}, it returns me only 1 value for {{{ y }}}
( in the case of III. the value returned for any {{{ x }}} never
changes, always {{{ y = 3 }}}, but it is always a unique value. )
E. II. and III. is the answer