Flora refers to the plants that grow in a specific geographical or political boundary. These plants are an integral part of the ecosystem, providing essential services such as oxygen production, food, habitat, and erosion control. Flora contributes to the overall biodiversity and functioning of the ecosystem.

**Explanation:**

**Flora and Fauna:**
- Flora and fauna are two distinct components of an ecosystem.
- Flora refers to all the plants present in a particular area, while fauna refers to the animal species.
- These two components are interdependent and together form the biodiversity of an ecosystem.

**Geographical or Political Boundary:**
- A geographical boundary refers to a physical feature that separates different regions, such as mountains, rivers, or coastlines.
- A political boundary, on the other hand, is a demarcation line established by governments to define territories or administrative divisions.

**Plants and their Distribution:**
- Plants have specific environmental requirements, and their distribution is influenced by various factors such as climate, soil type, sunlight, and water availability.
- Different plant species have different tolerances and preferences for these factors.
- As a result, plant communities vary across different geographical or political boundaries.

**Ecosystems and Flora:**
- An ecosystem is a complex network of living organisms and their physical environment, interacting and functioning together.
- Flora plays a vital role in the functioning of ecosystems.
- Plants are the primary producers in the food chain, converting sunlight into chemical energy through photosynthesis.
- They provide food and habitat for a variety of organisms, including insects, birds, mammals, and other plant species.
- Additionally, plants contribute to nutrient cycling, soil formation, and erosion control.

**Terrestrial Ecosystem:**
- A terrestrial ecosystem refers to an ecosystem that exists on land, including forests, grasslands, deserts, and wetlands.
- Flora is a major component of terrestrial ecosystems, as it forms the foundation of the food web and provides critical services.

Therefore, the correct answer is option 'C' - flora.

Flora is habitat and distribution of plants in a given area... NCERT page 14