If you want to couple a second trailer to your combination vehicle, secure it by using?

Answer: C — Either answer can be correct

The key idea is that a second trailer in a combination vehicle must be secured with a reliable coupling method, and you may use the primary locking mechanism or the backup linkage depending on the setup. The kingpin is the main locking connection that attaches the trailer to the hitch or dolly, while safety chains provide a backup link to prevent separation if the primary connection fails. Some configurations use the kingpin as the primary means to secure the second trailer, others rely on safety chains as the primary securement. In practice, you must use the method appropriate to your equipment and ensure the connection is secure and properly wired, which is why both approaches can be correct depending on the design of your combination. Note: the hitch ball is not typically used for securing a second trailer in doubles and triples.