Final answer:
30 milligrams is equal to 0.03 grams, so the correct answer is Option A (0.03g). Other options do not represent the correct conversion from milligrams to grams or kilograms.
Step-by-step explanation:
The student has asked to convert 30 milligrams (mg) to other mass units and identify which one is equal to 30 mg. To explain this, we need to understand the metric unit conversions. One milligram (1 mg) is 1/1000th of a gram (g), so there are 1000 mg in 1 g. Therefore, 30 mg is equal to 30/1000 g, which simplifies to 0.03 g. Option A (0.03g) is the correct answer. Other options can be eliminated; for instance, 0.03 kilograms (kg) would be equal to 30 g, not 30 mg; 0.003 g is 3 mg; and 0.003 kg is 3000 mg, all of which are incorrect for the given question.