Which of the following is a function?
a. (-2,3), (0,3), (1,6), (1,-6)
b. (-2,4), (0,3), (1,6), (-1,2)
c. (1,3), (2,4), (1,5), (2,3)
d. (1,-1), (2,-2), (1,-3), (4,-4)

  B. (-2,4), (0,3), (1,6), (-1,2)

Step-by-step explanation:

The list of first numbers for a function is a list of unique numbers.

  A: 1 is repeated

  B: the 4 pairs have 4 different first numbers: {-2, -1, 0, 1}

  C: 1 and 2 are repeated

  D: 1 is repeated

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step-by-step explanation: