Read the passage given below carefully and answer the questions that follow (Q. Nos. 129 to 135) by selecting the correct/most appropriate options.

Water is the core of life; hence water must be central to our spiritual thinking. Water is not only most of earth, but also most of life. Therefore water conservation must be our deepest concern.

The Himalayan mountain range is among the highest, youngest and most fragile ecosystem of the planet. The Himalayas have given us some of the great river systems of the earth including the Indus, Ganga, Brahmaputra, Nu Salween, Yangtze and the Mekong. The Himalayas are also called the 'Third Pole', for they contain the largest mass of ice and snow outside the earth's polar region, the north and south poles. There is a permanent snowline above 5,000 metres. Some of the glaciers in the region are the longest outside the two poles.

The Himalayas serve as water towers, providing water on a sustained basis to more than 1,000 million people and millions of hectares of land in South Asia. The greenery, benevolent climate, highly productive ecosystems, food production and overall happiness in South Asia are in fact, attributable to the bounty of the Himalayas. They are not only beautiful; they are life-givers. Little wonder that they are venerated as the abode of gods.

To keep the Third Pole preserved through assured conservation is one of the greatest challenges for the contemporary world. Himalayan mountains are a common but fragile natural resource. As mountain ecosystems have enormous bearing on the earth's systems, their special care, regeneration and conservation of their pristine resources would only bring more happiness, peace and prosperity to large parts of the world. In Agenda 21, Chapter 13 of the United Nations, the importance of mountains is underlined: "mountain environments are essential to the survival of global ecosystems."

The Himalayas in the state of Uttarakhand are especially rich in water resources. This area is home to dozens of perennial streams and numerous other rain-fed rivers along with innumerable rivulets, waterfalls and ponds, etc.

Which part of speech is the underlined word in the following sentence ?

The area is home to dozens of perennial streams.