The correct answer is option 'C': Near Threatened.

Explanation:
Grizzled giant squirrel (Ratufa macroura) falls under the IUCN (International Union for Conservation of Nature) category of Near Threatened. This category indicates that the species is not currently classified as critically endangered, endangered, or vulnerable, but it is close to qualifying for one of these categories in the near future if conservation efforts are not strengthened.

Endangered species are those that face a very high risk of extinction in the wild, while vulnerable species have a lower risk but are still facing significant threats. Near Threatened species are those that are close to meeting the criteria for vulnerable, but they do not yet fulfill all the requirements.

Now, let's understand why the Grizzled giant squirrel is categorized as Near Threatened:

Habitat Loss:
- One of the major threats to the Grizzled giant squirrel is habitat loss and degradation due to deforestation, urbanization, and agricultural expansion.
- The species primarily inhabits tropical forests and is dependent on a healthy forest ecosystem for its survival.
- As forests are cleared for various human activities, the squirrel's habitat becomes fragmented and reduced, leading to a decline in population.

Hunting and Poaching:
- The Grizzled giant squirrel is also hunted for its meat, skin, and other body parts.
- Despite legal protection in many countries, illegal hunting and poaching still pose a significant threat to the species.

Climate Change:
- Climate change and its associated impacts, such as alteration in rainfall patterns and increased frequency of extreme weather events, can negatively affect the squirrel's habitat and food availability.

Conservation Efforts:
- While the Grizzled giant squirrel is not currently classified as critically endangered, conservation efforts are crucial to prevent its population decline.
- Initiatives like protected areas, habitat restoration, and anti-poaching measures are being implemented to safeguard the species.

In conclusion, the Grizzled giant squirrel is categorized as Near Threatened because it is not currently critically endangered, endangered, or vulnerable, but it faces significant threats such as habitat loss, hunting, and climate change. Continued conservation efforts are necessary to ensure the long-term survival of this species.