State the number of significant figures in each of the following measurements: 4.5m, 0.0004L, 805lb, 204.52g, 625000mm, 34.80km.
a. 2, 1, 3, 5, 6, 4
b. 1, 3, 3, 5, 6, 4
c. 2, 1, 4, 5, 6, 3
d. 1, 4, 3, 5, 6, 2