Explanation:
we have no continuous curve here, the supposed function only consists of a few data pair points. and that is absolutely ok.
any function just maps a set of x (input) values to a set of y (function result) values.
A.
yes, it is a function, because every "used" x value has exactly 1 assigned y value.
when we draw a vertical line and move it across the grid, there are never 2 or more of the points in the line. always only one.
the opposite (every y value has exactly 1 x value as origin) is NOT necessary to be a function. but it would have to be true for the inverse function to be a function too.
B.
the domain is the interval or set of all valid x values.
since we have only single points, it is a set here :
{-4, -3, -2, 0, 2, 3}
C.
the range is the interval or set of all valid y values :
{-3, -1, 0, 2, 3}
D.
as we can see on the chart, the only point with x value = 2 has the y value = -3.
so,
y = -3 when x = 2
or formally
f(2) = -3