Final answer:
The correct marking for a system containing flammable refrigerant is a minimum of 10 centimeters in both directions on the process tubes or service connection.
Step-by-step explanation:
A system containing a flammable refrigerant must have the process tubes or service connection marked with a color marking that extends a minimum of 10 centimeters in both directions. The correct answer is (b) 10 centimeters. This safety measure helps in the identification and proper handling of systems with flammable substances to prevent accidents during maintenance or service operations.