Question: Coverage of which international situation from 2015 earned the Pulitzer prize for the photojournalist Sergey Ponomarev?

Context articles: Michel duCille
Larry C. Price
Daniel Berehulak
Pulitzer Prize for Photography
European migrant crisis
David S. Rohde
William Snyder (photojournalist)
Sergey Ponomarev (photographer)
Sergey Ponomarev
Pulitzer Prize for Breaking News Photography

Michel du Cille (January 24, 1956 – December 11, 2014) was a Jamaican-born American photojournalist who won three Pulitzer Prizes.
 He shared the 1986 Pulitzer Prize for Spot News Photography with fellow "Miami Herald" staff photographer Carol Guzy for their coverage of the November 1985 eruption of Colombia's Nevado del Ruiz volcano.
 He won the 1988 Feature Photography Pulitzer for a photo essay on crack cocaine addicts in a Miami housing project ("photographs portraying the decay and subsequent rehabilitation of a housing project overrun by the drug crack").
 As "du Cille" he shared the 2008 Pulitzer Prize for Public Service with "Washington Post" reporters Dana Priest and Anne Hull, for "exposing mistreatment of wounded veterans at Walter Reed Hospital, evoking a national outcry and producing reforms by federal officials."
Larry C. Price (born February 23, 1954) is an American photojournalist who has won two Pulitzer Prizes.
 In 1981 he won the Pulitzer Prize in Spot News Photography, recognizing images from Liberia published by the Fort Worth "Star-Telegram".
 In 1985 he won the Pulitzer Prize for Feature Photography for images from war-torn Angola and El Salvador published by "The Philadelphia Inquirer".
Daniel Berehulak (born 1975) is an Australian photographer and photojournalist based in New Delhi.
 A native of Sydney, Australia and a regular contributor to "The New York Times" he has visited more than 60 countries covering history-shaping events, including the Iraq and Afghan wars, the trial of Saddam Hussein, child labour in India and the return of Benazir Bhutto to Pakistan.
 He has also documented numerous social issues and people coping with the aftermath of disasters, including the Japan tsunami and the Chernobyl nuclear fallout.
 In 2015, he was awarded the Pulitzer Prize for feature photography for his coverage of the Ebola epidemic in West Africa, and was a Pulitzer Prize finalist for his coverage of the Pakistan floods in 2010.
 His photography has earned five World Press Photo awards and he has twice been named Photographer of the Year by Pictures of the Year International (2014 and 2015).
 In 2016, he was named Photojournalist of the Year (large-circulation publications) in the National Press Photographers Association’s Best of Photojournalism contest.
The Pulitzer Prize for Photography was one of the American Pulitzer Prizes annually awarded for journalism.
 It was inaugurated in 1942 and replaced by two photojournalism prizes in 1968: the Pulitzer Prize for Feature Photography and "Pulitzer Prize for Spot News Photography".
 The latter was renamed for Pulitzer Prize for Breaking News Photography in 2000.
The European migrant crisis, or the European refugee crisis, is a term given to a period beginning in 2015 when rising numbers of people arrived in the European Union (EU), travelling across the Mediterranean Sea or overland through Southeast Europe.
 These people included asylum seekers, but also others, such as economic migrants and some hostile agents, including Islamic State militants disguised as refugees or migrants.
David Stephenson Rohde (born August 7, 1967) is an American author and investigative journalist who currently serves as the online news director for "The New Yorker".
 While a reporter for "The Christian Science Monitor", he won the Pulitzer Prize for International Reporting in 1996 for his coverage of the Srebrenica massacre.
 From 2002 until 2005, he was co-chief of "The New York Times"' South Asia bureau, based in New Delhi, India.
 He later contributed to the newspaper's team coverage of Afghanistan and Pakistan that received the 2009 Pulitzer Prize for International Reporting and was a finalist in his own right in the category in 2010.
 He is also a global affairs analyst for CNN.
William Snyder is a four-time Pulitzer Prize-winning photojournalist and former Director of Photography for The Dallas Morning News.
 Snyder won a Pulitzer Prize for Explanatory Journalism in 1989 along with reporter David Hanners and artist Karen Blessen for their special report on a 1985 airplane crash, the follow-up investigation, and the implications for air safety.
 In 1991, he won the Pulitzer Prize for Feature Photography for his pictures of ill and orphaned children living in desperate conditions in Romania.
 In 1993, Snyder and Ken Geiger won the Pulitzer Prize for Spot News Photography for their photographic coverage of the 1992 Summer Olympics in Barcelona, Spain.
 As Photo Director he oversaw the Morning News photo staff's 2006 Pulitzer-winning coverage of Hurricane Katrina.
 In the Spring of 2008, Snyder took the buyout at the Dallas Morning News and returned to his alma mater, the Rochester Institute of Technology, where he is now the chair in the Photojournalism BFA program.
Sergey Igorevich Ponomarev (Russian: Сергей Игоревич Пономарёв , 11 December 1980, Moscow) is a Russian photographer.
 In 2016 he shared a Pulitzer Prize for Breaking News Photography with Mauricio Lima, Tyler Hicks, and Daniel Etter "For photographs that captured the resolve of refugees, the perils of their journeys and the struggle of host countries to take them in."
 Specifically, their coverage of the European migrant crisis, produced for The New York Times, was cited.
 He became the second individual Pulitzer Prize winner from Russia since 1992, after Alexander Zemlianichenko (1997).
 In 2017, he was awarded the Robert Capa Gold Medal (shared with Bryan Denton) for his coverage of the war in Iraq.
Sergey Ponomarev (Russian: Серге́й Пономарев ) is a former Russian football player.
The Pulitzer Prize for Breaking News Photography is one of the American Pulitzer Prizes annually awarded for journalism.
 From 2000 it has used the "breaking news" name but it is considered a continuation of the Pulitzer Prize for Spot News Photography, which was awarded from 1968 to 1999.
 Prior to 1968, a single Prize was awarded for photojournalism, the Pulitzer Prize for Photography, which was replaced in that year by Pulitzer Prize for Spot News Photography and Pulitzer Prize for Feature Photography.