Answer:
The correct answer is A
Step-by-step explanation:
In the given sentence, the word "infirmary's" is used to indicate possession or ownership. The word is correctly used in its singular possessive form to refer to the emergency room belonging to the infirmary. Since there is no indication that there are multiple infirmaries, the possessive form "infirmary's" is appropriate.
The other answer choices, B) "infirmaries," C) "infirmaries'," and D) "infirmarys," are incorrect because they either use the plural form of "infirmary" or incorrectly use the possessive form.
the original sentence is grammatically correct and does not require any changes.