Extract the answer to the question from the following context. Question: What is the type of thing that antigens fight against? Context: Resistance to infection (immunity) may be acquired following a disease, by asymptomatic carriage of the pathogen, by harboring an organism with a similar structure (crossreacting), or by vaccination. Knowledge of the protective antigens and specific acquired host immune factors is more complete for primary pathogens than for opportunistic pathogens. There is also the phenomenon of herd immunity which offers a measure of protection to those otherwise vulnerable people when a large enough proportion of the population has acquired immunity from certain infections.
Ans: pathogen

Extract the answer to the question from the following context. Question: What type of enjoyment were people getting out of Greek and Roman writings? Context: Despite these crises, the 14th century was also a time of great progress in the arts and sciences. Following a renewed interest in ancient Greek and Roman texts that took root in the High Middle Ages, the Italian Renaissance began. The absorption of Latin texts had started before the Renaissance of the 12th century through contact with Arabs during the Crusades, but the availability of important Greek texts accelerated with the capture of Constantinople by the Ottoman Turks, when many Byzantine scholars had to seek refuge in the West, particularly Italy.
Ans: renewed

Extract the answer to the question from the following context. Question: Why might it have been hard to spot a fish? Context: The climate of the Cretaceous is less certain and more widely disputed. Higher levels of carbon dioxide in the atmosphere are thought to have caused the world temperature gradient from north to south to become almost flat: temperatures were about the same across the planet. Average temperatures were also higher than today by about 10C. In fact, by the middle Cretaceous, equatorial ocean waters (perhaps as warm as 20 C in the deep ocean) may have been too warm for sea life,[dubious discuss][citation needed] and land areas near the equator may have been deserts despite their proximity to water. The circulation of oxygen to the deep ocean may also have been disrupted.[dubious discuss] For this reason, large volumes of organic matter that was unable to decompose accumulated, eventually being deposited as "black shale".
Ans: equatorial ocean waters (perhaps as warm as 20 C in the deep ocean) may have been too warm for sea life

Extract the answer to the question from the following context. Question: what is the second to last event mentioned? Context: SC Bern is the major ice hockey team of Bern who plays at the PostFinance Arena. The team has ranked highest in attendance for a European hockey team for more than a decade. The PostFinance Arena was the main host of the 2009 IIHF Ice Hockey World Championship, including the opening game and the final of the tournament.
Ans: the opening game