Answer
This is a function.
Work Step by Step
A function is a correspondence between a first set, called the domain,
and a second set, called the range,
such that EACH member of the domain corresponds to EXACTLY ONE member of the range.
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Keywords are emphasized.
We see from the definition of the correspondence that
EACH input from the domain has an arrow pointing from it to a value in the range.
and
only ONE arrow originates from each member of the domain.
This is a function.
NOTE:
Don't let the multiple incoming arrows in the range confuse you.
The definition focuses only on the members of the domain:
1. Is every member of the domain awarded a value from the range?
2. Is there only one value awarded to each member?
If the answer to both questions is yes, we have a function.