Which of the following is not required by the highway traffic act to be carried in a commercial motor vehicle?

The safety standard certificate is not a requirement to be carried in a commercial motor vehicle as per the highway traffic act. This document typically serves as proof that the vehicle meets safety regulations, but it is not mandated to be in the vehicle at all times.

On the other hand, having a legible copy of the CVOR certificate, the vehicle registration or a true copy, and the original insurance certificate is essential. The CVOR (Commercial Vehicle Operator's Registration) certificate provides information about the operator's compliance with safety regulations, while the vehicle registration proves that the vehicle is legally registered. The original insurance certificate is crucial as it demonstrates that the vehicle is insured, fulfilling legal requirements for operating the vehicle on public roads.