Explanation: Sikkim, a state in northeastern India, is renowned for its rugged and mountainous terrain. The geography of Sikkim is dominated by the Kanchenjunga massif, which is the third-highest mountain in the world and forms a significant part of the state's landscape. The term "perpetually snow-covered" refers to the condition where the mountains are covered with snow throughout the year, without any significant melting periods. This is a common feature in high-altitude regions where the temperature remains below freezing point for most of the year.
The correct answer to the question is "Covered." This term accurately describes the state of the mountains being perpetually covered with snow. The use of "covered" is grammatically correct as it is the past participle form of the verb "cover," which fits the context of the sentence. The sentence is describing the state of the mountains, and "covered" is the appropriate form to use in this context.
The other options are incorrect for the following reasons:
- "Cover" (Option B) is the base form of the verb and does not fit grammatically in the sentence.
- "Those" (Option C) is a demonstrative pronoun and does not fit the context of the sentence, which is describing the state of the mountains.
- "Cave" (Option D) is unrelated to the context of the sentence, which is discussing the snow-covered condition of the mountains.
Understanding the geographical features of Sikkim is crucial for comprehending the state's unique topography and its impact on the local environment and biodiversity. The perpetually snow-covered mountains play a significant role in the state's climate, water resources, and ecological systems.