Limits and Fits System:

Limits and Fits system is used to ensure that the mating parts fit together properly. It consists of two parts: the basic size and the tolerance. The basic size represents the nominal value of the part, while the tolerance represents the allowable deviation from that nominal value.

Basic Shaft System:

The basic shaft system is a type of limits and fits system where the shaft is considered the basic part. It means that the shaft's size is the nominal value, and the hole's size is considered the deviation. There are two types of deviations, upper deviation and lower deviation. The upper deviation is the difference between the maximum limit of the hole and the actual size of the hole. The lower deviation is the difference between the minimum limit of the hole and the actual size of the hole.

Answer Explanation:

In the given question, it is asked which of the following statements is true for the basic shaft system. The correct answer is option B, which states that the upper deviation is zero. It means that the maximum limit of the hole and the actual size of the hole are the same. The lower deviation can be any value, but the upper deviation is zero.

This type of system is used when the shaft's size is critical, and it is easier to control the hole's size. It ensures that the shaft fits the hole perfectly and eliminates the possibility of any play.

Conclusion:

In conclusion, the basic shaft system is used in limits and fits system when the shaft's size is critical, and it is easier to control the hole's size. The upper deviation is zero in this system, and it ensures that the shaft fits the hole perfectly without any play.