The scale that will produce the smallest drawing would be b) 1mm:50m.
First, I converted all the measurements to centimeters:
a) 1cm:500cm
b) 0.01cm:5000cm
c) 5cm:1000cm
d) 10cm:2500cm
Then, you divide the scales:
a) 0.002
b) 0.000002
c) 0.005
d) 0.004
B is the smallest number, meaning it will be the smallest scale.