instruction:
In this task, you are given a question and a context passage. You have to answer the question based on the given passage.
question:
Why do birds possess gizzards?, 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.
answer:
contains swallowed stones for grinding food to compensate for the lack of teeth

question:
what field of study is mentioned second to last?, Context: Muslim physicians contributed to the field of medicine, including the subjects of anatomy and physiology: such as in the 15th century Persian work by Mansur ibn Muhammad ibn al-Faqih Ilyas entitled Tashrih al-badan (Anatomy of the body) which contained comprehensive diagrams of the body's structural, nervous and circulatory systems; or in the work of the Egyptian physician Ibn al-Nafis, who proposed the theory of pulmonary circulation. Avicenna's The Canon of Medicine remained an authoritative medical textbook in Europe until the 18th century. Abu al-Qasim al-Zahrawi (also known as Abulcasis) contributed to the discipline of medical surgery with his Kitab al-Tasrif ("Book of Concessions"), a medical encyclopedia which was later translated to Latin and used in European and Muslim medical schools for centuries. Other medical advancements came in the fields of pharmacology and pharmacy.
answer:
pharmacology

question:
What was Kerry's focus during the 96th year of the 20th century?, Context: In 1996, Kerry faced a difficult re-election fight against Governor William Weld, a popular Republican incumbent who had been re-elected in 1994 with 71% of the vote. The race was covered nationwide as one of the most closely watched Senate races that year. Kerry and Weld held several debates and negotiated a campaign spending cap of $6.9 million at Kerry's Beacon Hill townhouse. Both candidates spent more than the cap, with each camp accusing the other of being first to break the agreement. During the campaign, Kerry spoke briefly at the 1996 Democratic National Convention. Kerry won re-election with 53 percent to Weld's 45 percent.
answer:
a difficult re-election fight against Governor William Weld