You are attempting to replace the oxygen cylinder in your truck. After removing the regulator from the old cylinder, removing the old cylinder, and placing the new cylinder in the oxygen compartment, you attempt to connect the regulator. The new cylinder has a yellow stripe around it instead of a green one but was stored with the green cylinders. You are unable to get the regulator to seat properly and it will not turn. You should: A. remove the cylinder and get a green cylinder
B. put the old cylinder back on the truck
C. attempt to force the regulator onto the cylinder
D. replace the oxygen regulator with a new one