Piles are structural elements used in civil engineering to transfer loads from a structure to the ground. They are typically long, slender columns made of materials such as concrete, steel, or timber. Piles can be classified into different types based on various criteria such as their material, shape, installation method, and load-carrying mechanism.

The given question asks about the classification of piles based on a certain function. Let's discuss the answer in detail:

Classification of Piles Based on Function:
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1. Load-Bearing Piles: These piles are primarily used to transfer the loads from a structure to the ground. They are designed to carry compressive, tensile, or both types of loads. Load-bearing piles can be further classified into:

a) End-Bearing Piles: These piles transfer the load through the lower tip or end of the pile to a hard or dense layer of soil or rock beneath. They rely on the bearing capacity of the underlying stratum. Examples include driven piles and bored piles with a socket in rock.

b) Friction Piles: These piles transfer the load to the surrounding soil through skin friction along the pile shaft. They rely on the adhesion and shearing resistance between the pile surface and the soil. Examples include driven piles in cohesive soils and bored piles in cohesive or granular soils.

c) Combination Piles: These piles combine the load-bearing mechanisms of both end-bearing and friction piles. They transfer load both through the tip and the shaft. Examples include driven piles in granular soils or weak rock formations.

2. Sheet Piles: These piles are used as retaining walls to provide lateral support to excavations or to retain soil or water. They are typically made of steel, concrete, or timber and are installed vertically or at a slight inclination into the ground.

3. Compaction Piles: These piles are used to densify loose or compressible soils. They are installed by driving or vibrating into the ground to compact the surrounding soil and improve its bearing capacity.

4. Anchor Piles: These piles are used to provide lateral or uplift resistance to structures. They are installed at an angle and anchor into stable soil or rock to counteract the applied loads.

5. Tension Piles: These piles are used to resist tensile forces in structures. They are designed to transfer the applied tension loads to the ground through their embedded length.

Conclusion:
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Based on the function, piles can be classified into various types such as load-bearing piles (end-bearing, friction, combination), sheet piles, compaction piles, anchor piles, and tension piles. Therefore, the correct answer to the given question is option 'C' - 8 types.