Direction: Read the following passage and fill up blanks with correct option. They extinguish fire by cutting the supply of__(21)__. Oxygen is needed for anything to __(22)__. So, if the supply of oxygen is cut off, the fire stops. For this, these cylinders contain carbon dioxide in form of __(23)__. These cylinders are commonly known as fire __(24)__.

• A. oxygen       
• B. carbon dioxide
• C. dust                             
• D. none of these