A linear function must satisfy the condition that the slope between any two points must remain the same.
Use this fact to find pairs of points which do not satisfy that condition. That will tell you which options are not linear functions.
A)
The slope of points (-2,0) and (1,-3) is -1 while the slope of points (1,-3) to (3,-6) is -3/2. Then, this is not a linear function.
B)
The slope of every pair of numbers here is 2. Then, this set represents a linear function.
C)
The slope of points (-7,-7) and (-3,-4) is 3/4 while the slope of points (-3,-4) and (0,-1) is -1. Then, this is not a linear function.
D)
The slope of points (3,3) and (5,4) is 1/2 while the slope of (5,4) and (7,6) is 1. Then, this is not a linear function.
Therefore, the answer is:
