Answer: b). 3
Explanation:
every real number is a sig fig (1-9)
Any zeros after real numbers behind the decimal are sig figs (0.340 = 3 sig figs)
Any zeros in between real numbers are sig figs (3402 = 4 sig figs)
If there is a clear decimal, every number in front of it are sig figs (100. = 3 sig figs) - this can also be expressed by a line above the zeros