Which of the following masses is the largest?
o 0.020 kg
0 20.0 mg
o 0.200 g
o 2000 ug

0.020 kg=20 g  this the largest

20.0 mg=.020g

.200g

2000ug

Explanation:

I am pretty sure that the factor that causes a decrease in the rate of dissolution is decreasing the surface area of the solute.  I bet that this is the most accurate option because the only thing that can lead lower rate of dissolution is when the area decreasing of the solute.
Hope it helps!