Which set of ordered pairs could be generated by an exponential function?

a.(-1,- 1/2), (0, 0), (1, 1/2), (2, 1)

b.(–1, –1), (0, 0), (1, 1), (2, 8)

c.(-1, 1/2), (0, 1), (1, 2), (2, 4)

d.(–1, 1), (0, 0), (1, 1), (2, 4)