Answer:
A. Left by 4 units
Explanation:
ƒ(x) = x²
It has a vertex at (0, 0), and the y-axis is the axis of symmetry
g(x) = x² + 8x + 16 = (x + 4)²
You have added 4 to the value of x, so you have shifted the graph four units to the left.
Thus, to make the graphs of ƒ(x) and g(x) coincide, you should shift ƒ(x) left by 4 units.
The diagram below shows ƒ(x) in red and g(x) in green.