The prefix "nano" is the smallest, measuring 1 x 10⁻⁹ m.
The prefix "micro" is next, measuring 1 x 10⁻⁶ m.
The prefix "milli" is the largest of these, measuring 1 x 10⁻³ m.
So, we are looking for "nano, micro, milli" which would be Option B.
Hope this helped ya!