How to safeguard a cargo carriage that is susceptible to polymerization?

 How to safeguard a cargo carriage that is susceptible to polymerization?

1) Suitable Inhibitors are added after cargo is loaded
2) Inhibitors ARE added before the cargo I loaded
3) ship do not carry such cargoes due to the serious threat to the environment
4)  Maintain cargo tank temperatures high enough not to cause polymerization

ANS___2) Inhibitors ARE added before the cargo I loaded