Teacher:In this task, you're given a passage, further information available on a particular linked term from the statement, and a question. Your job is to generate the answer to the question by using the information provided. If there is no clear answer obtainable, output 'none'.
Teacher: Now, understand the problem? Solve this instance: Passage: Port is produced from grapes grown and processed in the demarcated Douro region. The wine produced is then fortified by the addition of a neutral grape spirit known as aguardente to stop the fermentation, leaving residual sugar in the wine, and to boost the alcohol content. The fortification spirit is sometimes referred to as brandy but it bears little resemblance to commercial brandies. The wine is then stored and aged, often in barrels stored in a Lodge (meaning "cellar") as is the case in Vila Nova de Gaia, before being bottled. The wine received its name, "port", in the later half of the 17th century from the seaport city of Porto at the mouth of the Douro River, where much of the product was brought to market or for export to other countries in Europe. The Douro valley where port wine is produced was defined and established as a protected region, and the name Douro thus an official appellation, in 1756, making it the third oldest, after Chianti (1716) and Tokaj (1730).
 Link Information: Modern wooden barrels for wine-making are made of French common oak (Quercus robur) or white oak (Quercus petraea) or from American white oak Question: What material are the barrels made from that store the wine as it is aging?
Student:
Answer: common oak