Rainfall patterns across a particular area mainly depends on :
(i) the prevailing wind patterns
(ii) the pattern of population density in the area
(iii) the amount of available groundwater in the area.

Options

A. (i) and (iii)
B. (i) and (ii)
C. (ii) and (iii)
D. Only (i)

Explanation

To determine the main factor that influences rainfall patterns across a particular area, we will analyze the three options provided:

1. **Prevailing Wind Patterns**:
- Wind patterns play a crucial role in determining how moisture is transported across regions. Winds can carry moist air from oceans or large bodies of water to land, where it can condense and lead to precipitation (rainfall). Therefore, this factor is significant in influencing rainfall patterns.

2. **Pattern of Population Density**:
- While population density can have various environmental impacts, it does not directly influence the climatic conditions that lead to rainfall. The density of people in an area does not affect the meteorological processes that create rain.

3. **Amount of Available Groundwater**:
- Groundwater is an important resource for ecosystems and human use, but it does not directly affect rainfall patterns. Groundwater levels are more a result of rainfall than a cause of it. Thus, this factor is not relevant to the question.

Based on this analysis, the correct answer is that rainfall patterns mainly depend on **the prevailing wind patterns**.

### Step-by-Step Solution:
1. **Identify the Factors**: Look at the three options provided: prevailing wind patterns, population density, and available groundwater.
2. **Evaluate Each Factor**:
- **Prevailing Wind Patterns**: Recognize that winds transport moisture and influence precipitation.
- **Population Density**: Understand that while it affects human activities, it does not influence weather patterns.
- **Available Groundwater**: Acknowledge that groundwater is a result of rainfall, not a cause.
3. **Determine the Main Factor**: Conclude that the factor that primarily influences rainfall patterns is the prevailing wind patterns.