Linear functions increase/decrease at a constant rate as time passes. Exponential functions increase/decrease at a faster and faster rate as time passes.
1) From both tables, you can see that the y-value is going up as the x-value increases. Also notice that the y-value in Set A increases by 25 for each x-value. That means Set A is a linear function, since the rate of increase is the same, 25. Set B doesn't increase by 25 each time, meaning it's rate is different from A, letting you eliminate answers B and C.
2) Now you're left with answers A and D. Set A is linear and Set B is exponential, and from the table, you can see that Set B increases faster than Set A (Set B goes from y=0.6 to y=375 from x=-1 to x=3, while Set A only goes from y=50 to y=150). That means the answer must be choice A.
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Answer: A) Set B is an exponential function and the values increase at a faster rate than Set A.