Correct Answer - Option 4 : Nominal size
Explanation:
The following terms used in the limit system are important from the subject point of view:
Nominal Size: It is the size of a part specified in drawing as a matter of convenience.
Basic size: It is the size of a part to which all limits of variations is applied to arrive at the final dimensioning of the mating parts. The nominal or basic size of a part is often the same.
Actual size: It is the actually measured dimension of the part. The difference between the basic size and the actual size should not exceed a certain limit, otherwise, it will interfere with the interchangeability of the mating parts.
Limits of sizes: There are two extreme permissible sizes for a dimension of the part. The largest permissible size for a dimension of the part is called upper or high or maximum limit. Whereas the smallest size of the part is known as a lower or minimum limit.
