Question: Which mountain has a summit as a tripoint of a territory controlled by India, China, and Pakistan: Sia Kangri or Gasherbrum III?

Context paragraphs:
Rimo Muztagh: The Rimo Muztagh is one of the most remote subranges of the Karakoram range.  The southern part of Rimo Muztagh is in the Kashmir portion of far northwestern India, also claimed by Pakistan.  The northern half, including the Rimo massif, is in the Siachen area (territory controlled by India).  It is far from major towns, and close to the militarily sensitive Siachen Glacier, so it has seen little exploration or climbing activity compared to, for example, the nearby Baltoro Muztagh.  The highest peak is Mamostong Kangri, 7,516 metres (24,659 feet).

Gasherbrum III: Gasherbrum III (Urdu: گاشر برم -3‎ ; ), surveyed as K3a, is a summit in the Gasherbrum massif of the Baltoro Muztagh, a subrange of the Karakoram on the border between Xinjiang, China and Gilgit-Baltistan, Pakistan.  It is situated between Gasherbrum II and IV.

Gasherbrum: Gasherbrum (Urdu: گاشر برم‎ ) is a remote group of peaks located at the northeastern end of the Baltoro Glacier in the Karakoram range of the Himalaya on the border of the Chinese-administered Shaksgam Valley and the Gilgit-Baltistan territory of Pakistan.  The massif contains three of the world's 8,000 metre peaks (if Broad Peak is included).  Although the word "Gasherbrum" is often claimed to mean "Shining Wall", presumably a reference to the highly visible face of Gasherbrum IV, it comes from "rgasha" (beautiful) + "brum" (mountain) in Balti, hence it actually means "beautiful mountain".

Liankang Kangri: Liangkang Kangri (also known as "Liankang Kangri") is a mountain peak in the Himalayas on the border between Bhutan and China, as well as at the southeastern end of territory claimed by both countries.  Liangkang Kangri is 7535 m high.  To the south, a ridge leads to the 7570 m Gangkhar Puensum 2 km to the south-southeast .  Due to the low saddle height of 234 m , Liangkang Kangri is not regarded as an independent mountain.  Westward a ridge leads to the 6680 m high Chumhari Kang.  The Liangkanggletscher on the northwest flank and the Namsanggletscher on the eastern flank of Liangkang Kangri form the headwaters of the Lhobrak Chhu, a source river of Kuri Chhu.  The glacier on the southwest flank belongs to the catchment area of Angde Chhu.

Gasherbrum I: Gasherbrum I (Urdu: ‎ ; ), surveyed as K5 and also known as Hidden Peak, is the 11th highest mountain in the world at 8080 m above sea level.  It is located on the Pakistani–Chinese border in Gilgit–Baltistan region of Pakistan and Xinjiang region of China.  Gasherbrum I is part of the Gasherbrum massif, located in the Karakoram region of the Himalaya.  Gasherbrum is often claimed to mean "Shining Wall", presumably a reference to the highly visible face of the neighboring peak Gasherbrum IV; but in fact it comes from "rgasha" (beautiful) + "brum" (mountain) in Balti, hence it actually means "beautiful mountain."

Karakoram: The Karakoram, or Karakorum is a large mountain range spanning the borders of Pakistan, India, and China, with the northwest extremity of the range extending to Afghanistan and Tajikistan.  It is located in the regions of Gilgit–Baltistan (Pakistan), Ladakh (India), and southern Xinjiang (China), and reaches the Wakhan Corridor (Afghanistan).  A part of the complex of ranges from the Hindu Kush to the Himalayan Range, it is one of the Greater Ranges of Asia.  The Karakoram is home to the four most closely located peaks over 8000m in height on earth: K2, the second highest peak in the world at 8611 m , Gasherbrum I, Broad Peak and Gasherbrum II.

Sia Kangri: Sia Kangri (7,442 m, 24,370 ft) is a mountain in the Baltoro Muztagh in the Karakoram.  Its summit is the tripoint of territory controlled by India, China and Pakistan where the Actual Ground Position Line between Indian and Pakistani forces meets Chinese-controlled territory.  Territories on all sides are disputed.  The land immediately to the southwest of the peak is claimed by both Pakistan and India and controlled by Pakistan.  The land to the northeast is part of the Trans Karakoram Tract, controlled by China under a 1963 border agreement with Pakistan but claimed by India.  The land to the southeast is claimed by Pakistan and India, but controlled by India, as a part of its Siachen glacier territory.

Machulo La: Machulo La is a mountain view point which is considered the most easiest way to view some of the most highest peaks of Himalayas and Karakoram mountains in a single glance such as K2, Broad Peak, Gasherbrum-I, Gasherbrum-II, Gasherbrum III, Gasherbrum IV, K7, K6 and Nanga Parbat.

Indira Col: The Indira Col (altitude 5,764 m ) is a col (mountain pass, also called "La" in the local language) on the Indira Ridge in the Siachen Muztagh in the Karakoram Range.  It is within 3 km of Sia Kangri to the west, the summit of which is the tripoint where territories controlled by India, Pakistan and China meet.

Teram Kangri: The Teram Kangri group is a mountain massif in the remote Siachen Muztagh, a subrange of the Karakoram range.  The high point of the group, and of the Siachen Muztagh, is Teram Kangri I.  The peak lies on the boundary between China and the disputed Siachen Glacier region near the line of control between India and Pakistan.  The northeast side of the peak is in Chinese-controlled territory, the southwest side in the disputed Siachen area currently controlled by India.

Supporting paragraphs: Sia Kangri Gasherbrum III
Answer: Sia Kangri