The correct answer is option 'C' - Local cubic rate. The cubic contents method is a cost estimation technique used in civil engineering to determine the cost of a structure. This method involves multiplying the total cubic contents of the structure by the local cubic rate to calculate the cost.

Here is a detailed explanation of each term involved in the cubic contents method:

1. Total cubic contents: The total cubic contents of a structure refers to the total volume of the building. It is calculated by multiplying the length, width, and height of each individual component of the structure and summing them up. The resulting value represents the total cubic contents or volume of the structure.

2. Local cubic rate: The local cubic rate is a factor that represents the cost per unit volume of construction in a specific area or locality. This rate varies from one location to another and depends on various factors such as material costs, labor costs, market conditions, and other regional factors. The local cubic rate is usually provided by local construction authorities or can be obtained through market research.

3. Cost of the structure: To determine the cost of the structure using the cubic contents method, the total cubic contents of the structure are multiplied by the local cubic rate. The resulting value gives an estimation of the cost of the structure based on the volume of construction.

The cubic contents method is commonly used in civil engineering for preliminary cost estimation purposes. It provides a rough estimate of the construction cost based on the volume of the structure and the prevailing rates in the local market. However, it is important to note that this method does not take into account other important cost factors such as design complexity, finishes, site conditions, and other project-specific variables. Therefore, it should be used as a starting point for cost estimation and further refined based on detailed project requirements and specifications.