Which of the following sets of vectors are bases for R³?
a) (3, 0, 0) , (6, 6, 0) , (9, 9, 9)
b) (4, 1, -4) , (8, 3, 4) , (12, 2, 5)
c) (3, -4, 4) , (6, 4, 4) , (0, -12, 4)
d) (2, 5, 7) , (2, 15, -3) , (0, 10, -10)