I NEED HELP PLEASE AND THANK YOU (asap) Which relation represents a linear function?

A) (5,6), (3,8), (1,10), (-1, 12)
B) (-3,1), -1,4), (1,9), (3,16)
C) (-2,0), (0,1), (2,3), (4,6)
D) (7,-1), (4,-3), (1,-6), (-2,-9)

The lengths of two sides of a triangle are 9 and 15. what can be said about the length of the third side? a. it must be greater than or equal to 6 and less than 24. b. it must be greater than or equal to 6 and at most 24. c. it must be greater than 6 and less than 24. d. it must be greater than 6 and at most 24.