The set of ordered pairs is a function of x because each x-value is paired with exactly one y-value. To keep the relation as a function of x, we need to make sure that each x-value is only paired with one y-value.
A. (-6, 1), (-1, 1): (-6, 1) would not work because it would create two y-values for the x-value of -5. (-1, 1) would work because it is not included in the original set of ordered pairs.
B. (-2, 2), (-1, 1): (-2, 2) would not work because it would create two y-values for the x-value of -2. (-1, 1) would not work because it is already included in the original set of ordered pairs.
C. (-3,0), (-1, 1): (-3, 0) would work because it is not included in the original set of ordered pairs. (-1, 1) would not work because it is already included in the original set of ordered pairs.
D. (-6, 1), (-5, 1): (-6, 1) would not work because it is not one of the answer choices in the set. (-5, 1) would not work because it is already included in the original set of ordered pairs.
Therefore, the answer is C: (-3,0), (-1, 1).