Question: Which mountain peak was explored first, Sunanda Devi or Annapurna II? 
Context: Annapurna South, also called Annapurna Dakshin or Moditse, is a mountain in the Annapurna Himal range of the Himalayas, and the 101st-highest mountain in the world.  It was first ascended in 1964, and is 7,219 m tall.  The nearby mountain Hiunchuli is in fact an extension of Annapurna South. Rongme Ngatra is the highest peak of the Chola Mountains in the Kham region of western Sichuan, China.  The peak's name in Mandarin Chinese is Que Er Shan () also the same name as the entire range, which has led to some translations of the mountain peak to Chola Mountain.  At 6,168 m , the mountain is the highest peak in the Chola Mountains, as well as the second highest in the greater Shaluli Mountains after Ge'nyen.  The mountain peak is flanked by glaciers to the north and east.  The north glacier terminates at 4,100 m above sea level, just above the nearby lake Yihun Lhatso.  Rongme Ngatra can be accessed from the town of Manigango in Dege County, Garze Prefecture. Cook Peak el.  9754 ft is a mountain peak in the Washburn Range of Yellowstone National Park.  The peak was named in 1922 by then superintendent Horace Albright to honor of Charles W. Cook, a member of the 1869 Cook–Folsom–Peterson Expedition which explored the Yellowstone park region.  1922 was the 50th anniversary of the park's creation, and Charles Cook, still living in Montana, attended ceremonies in the park.  Prior to 1922, the peak had been named "Thompson Peak" by Philetus Norris in 1880 and "Storm Peak" by members of the Arnold Hague Geological Surveys in 1885. Bolna (Lule Sami: "Bållná" ) is a mountain in the Saltfjellet mountain range in the municipality of Rana in Nordland county, Norway.  The mountain peak reaches 1460 m above sea level, and is located just north of the Arctic Circle inside Saltfjellet–Svartisen National Park.  The mountain peak is located less than 2 km west of the municipal border with Saltdal and about 15 km west of the border with Sweden. Pisang is a village development committee in Manang District in the Gandaki Zone of northern Nepal.  At the time of the 2011 Nepal census it had a population of 307  people living in 105 individual households.  The village is located in the Marshyangdi River valley, directly south of Pisang Peak, north of Annapurna II, and west of Paungda Danda. Annapurna IV is a mountain of the Annapurna range in the Himalayas.  It is near Annapurna II.  It was first climbed in 1955 by a German expedition led by Heinz Steinmetz via the North Face and Northwest Ridge.  The summit party comprised Steinmetz, Harald Biller, and Jürgen Wellenkamp. The Annapurna Circuit is a trek within the Annapurna mountain range of central Nepal.  The total length of the route varies between 160–230 km (100-145 mi), depending on where motor transportation is used and where the trek is ended.  The trek rises to an altitude of 5,416m on the Thorung La pass, touching the edge of the Tibetan plateau.  This trek crosses two different river valleys and encircles the Annapurna massif, crossing Thorung La (5416m/17769 ft), the highest pass on this trek.  Practically all trekkers hike the route anticlockwise, as this way the daily altitude gain is slower, and crossing the high Thorong La pass is easier and safer.  The mountain scenery, seen at close quarters includes the Annapurna Massif (Annapurna I-IV), Dhaulagiri, Machhapuchhre, Manaslu, Gangapurna, Tilicho Peak, Pisang Peak, and Paungda Danda.  Numerous other peaks of 6000-8000m in elevation rise from the Annapurna range. Rishi Pahar is a Himalayan mountain peak, located in the Pithoragarh district of Uttarakhand state in India.  It lies at the northeast corner of the ring of peaks surrounding the Nanda Devi Sanctuary, and on the eastern rim of the Nanda Devi Biosphere Reserve, just south of Trishuli and Hardeol.  The Milam Glacier lies on its east flank.  It marks the triple divide between the Milam, Dunagiri, and Uttari Rishi Ganga valleys.  Rishi Pahar means 'The Peak of Saint' in Hindi. Annapurna II is part of the Annapurna mountain range, and is the eastern anchor of the range.  It was first climbed in 1960 by a British/Indian/Nepalese team led by J. O. M. Roberts via the West Ridge, approached from the north.  The summit party comprised Richard Grant, Chris Bonington, and Sherpa Ang Nyima.  In terms of elevation, isolation (distance to a higher summit, namely Annapurna I, 30.5 km ) and prominence (2437 m ), Annapurna II does not rank far behind Annapurna I Main, which serves as the western anchor.  It is a fully independent peak, despite the close association with Annapurna I Main which its name implies. Sunanda Devi (Hindi: सुनन्दा देवी ) previously known as Nanda Devi East is the lower of the two adjacent peaks of the highest mountain in Uttarakhand and second highest mountain in India; Nanda Devi is its higher twin peak.  Nanda Devi and Sunanda Devi are part of the Garhwal Himalayas, and are located in the state of Uttarakhand.  The graceful peaks of twin mountains are visible from almost everywhere in Kumaon.  The first ascent to the Sunanda Devi peak in recorded history appears to be in 1939 by Jakub Bujak and Janusz Klarner.  The elevation of Sunanda Devi is 7434 m and its prominence is 260 m .
Answer: Sunanda Devi