Rate of payment for various types of excavation:

In civil engineering, excavation is a common process that involves the removal of soil, rock, or other materials from a site to create space for construction or other activities. The rate of payment for excavation work varies depending on the type of material being excavated and the difficulty of the job. In this case, the correct answer is option 'D', which means that the rate of payment is made for 100 cubic meters in all the mentioned cases, including earth work in excavation, rock cutting, and excavation in trenches for foundation. Let's discuss each type of excavation in detail:

a) Earth work in excavation:
Earth work in excavation refers to the process of removing soil or earth from a construction site. It is typically done to create a level surface for building foundations, roads, or other structures. The rate of payment for earth work in excavation is calculated per 100 cubic meters. This means that the payment is made for every 100 cubic meters of soil or earth removed from the site. The rate may vary depending on factors such as the type of soil, the depth of excavation, and the distance of transportation.

b) Rock cutting:
Rock cutting involves the removal of solid rock or hard materials from a construction site. It is a more challenging and time-consuming process compared to earth work in excavation. The rate of payment for rock cutting is also calculated per 100 cubic meters. This means that the payment is made for every 100 cubic meters of rock removed from the site. The rate for rock cutting is typically higher than that for earth work due to the increased difficulty and specialized equipment required for the job.

c) Excavation in trenches for foundation:
Excavation in trenches for foundation is a specific type of excavation carried out for building foundations. It involves the removal of soil or earth to create trenches of specific dimensions for the placement of foundation footings or walls. The rate of payment for excavation in trenches for foundation is also calculated per 100 cubic meters. This means that the payment is made for every 100 cubic meters of soil or earth removed to create the trenches.

Summary:
In summary, the rate of payment for excavation work is determined based on the quantity of material removed from the site. In the case of earth work in excavation, rock cutting, and excavation in trenches for foundation, the rate of payment is made per 100 cubic meters. This allows for a standardized measurement and calculation of the payment based on the volume of material excavated.