Problem: Extract the answer to the question from the following context. Question: The link between South and North America had what effect on the Atlantic Ocean? Context: South America became linked to North America through the Isthmus of Panama during the Pliocene, bringing a nearly complete end to South America's distinctive marsupial faunas. The formation of the Isthmus had major consequences on global temperatures, since warm equatorial ocean currents were cut off and an Atlantic cooling cycle began, with cold Arctic and Antarctic waters dropping temperatures in the now-isolated Atlantic Ocean. Africa's collision with Europe formed the Mediterranean Sea, cutting off the remnants of the Tethys Ocean. Sea level changes exposed the land-bridge between Alaska and Asia. Near the end of the Pliocene, about 2.58 million years ago (the start of the Quaternary Period), the current ice age began. The polar regions have since undergone repeated cycles of glaciation and thaw, repeating every 40,000100,000 years.

A: cooling cycle

Problem: Extract the answer to the question from the following context. Question: How is a hummingbird different from most birds on excreting waste? Context: Like the reptiles, birds are primarily uricotelic, that is, their kidneys extract nitrogenous waste from their bloodstream and excrete it as uric acid instead of urea or ammonia through the ureters into the intestine. Birds do not have a urinary bladder or external urethral opening and (with exception of the ostrich) uric acid is excreted along with feces as a semisolid waste. However, birds such as hummingbirds can be facultatively ammonotelic, excreting most of the nitrogenous wastes as ammonia. They also excrete creatine, rather than creatinine like mammals. This material, as well as the output of the intestines, emerges from the bird's cloaca. The cloaca is a multi-purpose opening: waste is expelled through it, most birds mate by joining cloaca, and females lay eggs from it. In addition, many species of birds regurgitate pellets. Males within Palaeognathae (with the exception of the kiwis), the Anseriformes (with the exception of screamers), and in rudimentary forms in Galliformes (but fully developed in Cracidae) possess a penis, which is never present in Neoaves. The length is thought to be related to sperm competition. When not copulating, it is hidden within the proctodeum compartment within the cloaca, just inside the vent. The digestive system of birds is unique, with a crop for storage and a gizzard that contains swallowed stones for grinding food to compensate for the lack of teeth. Most birds are highly adapted for rapid digestion to aid with flight. Some migratory birds have adapted to use protein from many parts of their bodies, including protein from the intestines, as additional energy during migration.

A: excreting most of the nitrogenous wastes as ammonia

Problem: Extract the answer to the question from the following context. Question: How have celebrities latched onto YouTube? Context: Both private individuals and large production companies have used YouTube to grow audiences. Independent content creators have built grassroots followings numbering in the thousands at very little cost or effort, while mass retail and radio promotion proved problematic. Concurrently, old media celebrities moved into the website at the invitation of a YouTube management that witnessed early content creators accruing substantial followings, and perceived audience sizes potentially larger than that attainable by television. While YouTube's revenue-sharing "Partner Program" made it possible to earn a substantial living as a video producerits top five hundred partners each earning more than $100,000 annually and its ten highest-earning channels grossing from $2.5 million to $12 millionin 2012 CMU business editor characterized YouTube as "a free-to-use... promotional platform for the music labels". In 2013 Forbes' Katheryn Thayer asserted that digital-era artists' work must not only be of high quality, but must elicit reactions on the YouTube platform and social media. In 2013, videos of the 2.5% of artists categorized as "mega", "mainstream" and "mid-sized" received 90.3% of the relevant views on YouTube and Vevo. By early 2013 Billboard had announced that it was factoring YouTube streaming data into calculation of the Billboard Hot 100 and related genre charts.

A: at the invitation of a YouTube management

Problem: Extract the answer to the question from the following context. Question: what natural occurrences are mentioned last? Context: The Exeter to Plymouth railway of the LSWR needs to be reopened to connect Cornwall and Plymouth to the rest of the UK railway system on an all weather basis. There are proposals to reopen the line from Tavistock to Bere Alston for a through service to Plymouth. On the night of 4 February 2014, amid high winds and extremely rough seas, part of the sea wall at Dawlish was breached washing away around 40 metres (130 ft) of the wall and the ballast under the railway immediately behind. The line was closed. Network Rail began repair work and the line reopened on 4 April 2014. In the wake of widespread disruption caused by damage to the mainline track at Dawlish by coastal storms in February 2014, Network Rail are considering reopening the Tavistock to Okehampton and Exeter section of the line as an alternative to the coastal route.

A:
coastal storms