In this task, you are given a question and a context passage. You have to answer the question based on the given passage.

Example Input: What is needed to prove the theory?, Context: In the early 11th century, the Muslim physicist Ibn al-Haytham (Alhacen or Alhazen) discussed space perception and its epistemological implications in his Book of Optics (1021), he also rejected Aristotle's definition of topos (Physics IV) by way of geometric demonstrations and defined place as a mathematical spatial extension. His experimental proof of the intromission model of vision led to changes in the understanding of the visual perception of space, contrary to the previous emission theory of vision supported by Euclid and Ptolemy. In "tying the visual perception of space to prior bodily experience, Alhacen unequivocally rejected the intuitiveness of spatial perception and, therefore, the autonomy of vision. Without tangible notions of distance and size for correlation, sight can tell us next to nothing about such things."
Example Output: vision

Example Input: neurons talk each other through, Context: The brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. Only a few invertebrates such as sponges, jellyfish, adult sea squirts and starfish do not have a brain; diffuse or localised nerve nets are present instead. The brain is located in the head, usually close to the primary sensory organs for such senses as vision, hearing, balance, taste, and smell. The brain is the most complex organ in a vertebrate's body. In a typical human, the cerebral cortex (the largest part) is estimated to contain 1533 billion neurons, each connected by synapses to several thousand other neurons. These neurons communicate with one another by means of long protoplasmic fibers called axons, which carry trains of signal pulses called action potentials to distant parts of the brain or body targeting specific recipient cells.
Example Output: axons

Example Input: Who did Cohen think like besides Barth?, Context: Anthropologists have contributed to the debate by shifting the focus of research: One of the first challenges for the researcher wishing to carry out empirical research in this area is to identify an appropriate analytical tool. The concept of boundaries is useful here for demonstrating how identity works. In the same way as Barth, in his approach to ethnicity, advocated the critical focus for investigation as being "the ethnic boundary that defines the group rather than the cultural stuff that it encloses" (1969:15), social anthropologists such as Cohen and Bray have shifted the focus of analytical study from identity to the boundaries that are used for purposes of identification. If identity is a kind of virtual site in which the dynamic processes and markers used for identification are made apparent, boundaries provide the framework on which this virtual site is built. They concentrated on how the idea of community belonging is differently constructed by individual members and how individuals within the group conceive ethnic boundaries.
Example Output:
Bray