Answer:
The line on the bottom and and the parabola on the top are functions.
Step-by-step explanation:
A function is when there is only one y value for each x value.
The Circle:
Take x = 5 for example. When you look there, there are two y-values for x=5:
y = -1 and y = 1. This is not possible, so the circle is not a function.
The Half-Circle:
Take x = 2 for example. When you look there, there are two y-values for x=2: y = 2 and y = -1. This is not possible, so the half-circle is also not a function.
The Helix (on the far left side):
Take x = -4 for example. When you look there, there are two y-values for x=-4: y = 4 and y = -3. This is not possible, so the helix is also not a function.
