What should be checked regarding the floor and cross members of a trailer?

The correct answer emphasizes the importance of ensuring that the trailer's floor is completely intact and free from any holes, while also highlighting that all cross members should be present, securely fastened, and in good condition. This is crucial for the structural integrity of the trailer as the floor and cross members work together to support the load being carried.

An intact floor without holes prevents cargo from falling through and maintains a safe environment for loading and unloading. The cross members provide support and stability for the floor, ensuring it can bear the weight of the cargo effectively. If any cross members are missing or not properly secured, it can lead to serious safety issues, including the risk of structural failure while the vehicle is in motion.

Checking for these conditions is a standard part of a pre-trip inspection to ensure safety on the road, compliance with regulations, and overall vehicle reliability. The other options suggest compromising on structural integrity in various ways, which is not acceptable for safe operation.