Final answer:
The correct way to write seven milligrams is 7 mg.
Step-by-step explanation:
In order to minimize the risk of a dosage error, the correct way to write seven milligrams is as 7 mg (option B).
Writing it as 0.7 mg (option A) would be incorrect because it represents a lower dosage.
Writing it as 7.0 mcg (option C) would also be incorrect because mcg (micrograms) is a smaller unit than milligrams.
Writing it as 7 gm (option D) would be incorrect because gm stands for grams, which is a larger unit than milligrams.