Answer:
A: Linear
B: Linear
C: Linear
Explanation:
So we have three functions:

To determine the type of graph for each function, simplify each of them and then we can determine whether it's linear or quadratic.
1)
We have:

This has a degree of 1. Quadratics have a degree of 2. In other words, quadratics have a x^2 term. There isn't one here, so this is a linear equation.
2)
We have:

Simplify:

Again, this is of degree 1. There is no x^2 term. Thus, this is also a linear equation.
3)
We have:

Simplify:

This has a degree of 1. There is no x^2 term. Thus, this is also a linear equation.