The correct answer is (c), Satopanth Glacier.
The Alaknanda River is one of the two main tributaries of the Ganges River. It originates from the Satopanth Glacier in the Garhwal Himalayas. The Satopanth Glacier is a large glacier located in the Garhwal Himalayas in the Indian state of Uttarakhand. It is the source of the Alaknanda River, one of the two main tributaries of the Ganges River. The glacier is about 20 kilometers long and 10 kilometers wide. It is a popular destination for trekking and mountaineering.
The other options are incorrect because they are not the source of the Alaknanda River.
(a) The Ralam Glacier is a glacier located in the Garhwal Himalayas in the Indian state of Uttarakhand. It is the source of the Ralam River, a tributary of the Alaknanda River.
(b) The Milam Glacier is a glacier located in the Garhwal Himalayas in the Indian state of Uttarakhand. It is the source of the Milam River, a tributary of the Alaknanda River.
(d) The Dunagiri Glacier is a glacier located in the Garhwal Himalayas in the Indian state of Uttarakhand. It is the source of the Dunagiri River, a tributary of the Alaknanda River.