Answer:
d) one microliter
Explanation: The advantage of the SI (International system of measurements) is that everything is in base 10, and the prefix indicates the power of 10.
For the volume, the base unit is the liter.
one microliter = 0.000001 liter (one millionth, 1 / 1000000, of a liter)
one deciliter = 0.1 liter (one tenth, 1/10, of a liter)
one liter = 1 liter
one milliliter = 0.001 liter (one thousand, 1/1000, of a liter)
As you can see, a microliter is by far the smallest of these units.
