**Core Concept**
The question is testing the management and immediate care of a patient who has experienced a grand mal seizure in a dental office, specifically regarding the administration of first aid and emergency medications.

**Why the Correct Answer is Right**
A grand mal seizure, also known as tonic-clonic seizure, is a type of generalized seizure characterized by muscle contractions and relaxations, loss of consciousness, and sometimes tongue biting or incontinence. In a dental office, the primary goal is to ensure the patient's safety and prevent injury. Correct administration of first aid, such as turning the patient onto their side to prevent aspiration and ensuring a safe environment, is crucial. In some cases, benzodiazepines like diazepam may be administered to help terminate the seizure, but this requires proper training and equipment.

**Why Each Wrong Option is Incorrect**

* **Option A:** This option is incorrect because it does not provide any information about the management of a grand mal seizure in a dental office. Without context, it is difficult to assess the validity of this option.
* **Option B:** This option is incorrect because it may cause more harm than good. Administering oxygen may be useful in some cases of seizure, but it is not a standard first aid measure for a grand mal seizure.
* **Option C:** This option is incorrect because it is not a standard first aid measure for a grand mal seizure. While maintaining a safe environment is crucial, simply "staying with the patient" does not provide any specific guidance on how to manage the situation.

**Clinical Pearl / High-Yield Fact**
It is essential for dental professionals to be trained in basic life support (BLS) and seizure first aid, including proper positioning of the patient and the administration of benzodiazepines when necessary.

**Correct Answer: B. Administer oxygen.**