Verified answer

You don't give the units. Hmm, can't be km, because 1 mm is one millionth of that.

Let me guess, milli means one thousandth so millimeter is one thousandth of a meter, or there are 1000 mm in a meter.

(3mm/1000mm/m) = 0.003 answer a)

But there are 10 mm in 1cm, so

(3 mm/10 mm/cm) = 0.3 cm answer c)

Information was missing, which is why no one but me answered.