Just to avoid some confusion: the first picture is a graph of function A, and the second picture is a graph of function B. 
Answer:
D. Function A is non-linear and Function B is linear. 
Step-by-step explanation:
A good way to find out if a function is linear is by graphing it. If you graph it and it is a straight line, then it is linear. 
So, let's graph the given points from the table of Function A and see if it forms a straight line. When you connect the dots, it's not straight, so Function A is non-linear. 
Now let's look at function B. We can graph that too with the given information from the equation - the slope is -1 and the y-intercept is 5. (If you are a bit confused on how to graph it, don't hesitate to ask!) It does form a straight line, so Function B is linear.