Refer to table 11-5. What is the minimum size single wall metal pipe vent required for an appliance that has a maximum input rating of 240,000 Btu where the vent extends 20` above the appliance and has no offsets?

Refer to table 11-5. What is the minimum size single wall metal pipe vent required for an appliance that has a maximum input rating of 240,000 Btu where the vent extends 20` above the appliance and has no offsets?