Step-by-step explanation:
the answer is B. y (4 + z)
Only 25 and 28 are functions.
A function must have only one y value per x value. For 26, the y value of 0 and multiple others have two different y values. For 27, all x values less than 0 have multiple y values.
For A B and C, you just plug in the given number
A

B

C

And for D, you set the equation to 26 and solve for n

I had to use x instead of n, but for D n=7. :)
Answer:
a
Step-by-step explanation: