Final answer:
Marissa should take the chart to Dr. Williams and have him write the order for the DPT injection before proceeding with the administration to maintain patient safety and legal compliance. The correct answer for the question is option (C).
Step-by-step explanation:
When Marissa, the medical assistant, checks the chart and discovers that the order for a DPT injection is not there, the correct course of action would be option C): Take the chart to the physician and have him write the order before administering the medication. It is crucial in medical practice to ensure that all medication orders are documented properly before administration to safeguard patient safety and maintain legal and professional compliance. Option B) is not appropriate because it is not within the medical assistant's scope of practice to write orders for medications, even as verbal orders to be signed later. Option A) disregards the importance of having a written order and could pose serious risks. Option D) is incorrect because an office manager is not qualified to write medical orders.