Práctica CDL air brakes

Your tractor has a dual air brake system. After a cold start, the primary gauge reads 120 psi and the secondary gauge reads 80 psi. When may you start driving?

• AAfter both systems reach at least 100 psi.
• BNow, because the primary system is above 100 psi.
• CNow, because both systems are above 60 psi.
• DAfter the secondary system reaches 125 psi.