TASK DEFINITION: In this task, you are given a question and a context passage. You have to answer the question based on the given passage.
PROBLEM: From what era, once thought devoid of animal life, was evidence of grazer populations discovered?, Context: Some paleontologists suggest that animals appeared much earlier than the Cambrian explosion, possibly as early as 1 billion years ago. Trace fossils such as tracks and burrows found in the Tonian period indicate the presence of triploblastic worms, like metazoans, roughly as large (about 5 mm wide) and complex as earthworms. During the beginning of the Tonian period around 1 billion years ago, there was a decrease in Stromatolite diversity, which may indicate the appearance of grazing animals, since stromatolite diversity increased when grazing animals went extinct at the End Permian and End Ordovician extinction events, and decreased shortly after the grazer populations recovered. However the discovery that tracks very similar to these early trace fossils are produced today by the giant single-celled protist Gromia sphaerica casts doubt on their interpretation as evidence of early animal evolution.

SOLUTION: the Tonian period

PROBLEM: Glass that has been covered with ash or soot on one one side to obscure light is called?, Context: Historically, pubs have been socially and culturally distinct from cafés, bars and German beer halls. Most pubs offer a range of beers, wines, spirits, and soft drinks and snacks. Traditionally the windows of town pubs were of smoked or frosted glass to obscure the clientele from the street but from the 1990s onwards, there has been a move towards clear glass, in keeping with brighter interiors.

SOLUTION: smoked

PROBLEM: Which happened first, the financial crisis or the City regaining lost ground?, Context: London's largest industry is finance, and its financial exports make it a large contributor to the UK's balance of payments. Around 325,000 people were employed in financial services in London until mid-2007. London has over 480 overseas banks, more than any other city in the world. Over 85 percent (3.2 million) of the employed population of greater London works in the services industries. Because of its prominent global role, London's economy had been affected by the Late-2000s financial crisis. However, by 2010 the City has recovered; put in place new regulatory powers, proceeded to regain lost ground and re-established London's economic dominance. The City of London is home to the Bank of England, London Stock Exchange, and Lloyd's of London insurance market.

SOLUTION:
financial crisis