Soil composition, grain size, and aggregation are important characteristics that determine the percolation and water holding capacity of the soil. Let's explore each of these characteristics and their influence on soil properties.

1. Soil Composition:
- Soil composition refers to the types and proportions of mineral particles, organic matter, air, and water in the soil.
- Different soil compositions have different properties that affect percolation and water holding capacity.
- For example, sandy soils have larger particles with larger pore spaces, allowing water to percolate quickly through the soil. On the other hand, clayey soils have smaller particles with smaller pore spaces, leading to slower percolation.
- Soils with higher organic matter content have better water holding capacity due to the ability of organic matter to retain moisture.

2. Grain Size:
- Grain size refers to the size of individual soil particles.
- Coarse-grained soils, such as sands and gravels, have larger particles with larger pore spaces, allowing water to drain quickly through the soil. These soils typically have high percolation rates but lower water holding capacity.
- Fine-grained soils, such as clays and silts, have smaller particles with smaller pore spaces, resulting in slower percolation. These soils tend to have higher water holding capacity due to the smaller pore spaces that can hold more water.

3. Aggregation:
- Aggregation refers to the arrangement of soil particles into clumps or aggregates.
- Well-aggregated soils have good structure with stable aggregates, allowing for better water infiltration and percolation.
- Soil aggregation improves the soil's ability to hold and retain water, as the aggregates create pore spaces that can hold both air and water.
- On the other hand, poorly aggregated soils have weak structure, leading to reduced percolation and water holding capacity.

In conclusion, the characteristics of soil composition, grain size, and aggregation play a significant role in determining both the percolation rate and water holding capacity of the soil. These factors interact with each other to influence the movement of water through the soil profile and the soil's ability to retain moisture. Therefore, the correct answer is option 'C' - percolation and water holding capacity of the soil.