The correct answer is: B. was dying
The patient was dying before the doctor came. This is because the verb “was dying” is in the past progressive tense, which is used to describe an action that was in progress at a specific time in the past. In this case, the specific time in the past is before the doctor came.
The other options are incorrect because they do not accurately describe the patient’s condition. The verb “dies” is in the simple present tense, which is used to describe an action that happens regularly or repeatedly. The verb “had died” is in the past perfect tense, which is used to describe an action that happened before another action in the past. The verb “had been dying” is in the past perfect progressive tense, which is used to describe an action that was in progress before another action in the past.
In conclusion, the correct answer is: B. was dying.