Answer:
D x2 + y2 = 4
Step-by-step explanation:
The following are the functions
y = 4
y = x - 4
y = x^2 - 4
but
x^2 + y^2 = 4 is not a function as there should be minimum one x value with two or more y values
But the above equation does not meet the criteria so this represent non-function
