Given a context passage, generate a question from the passage such that its answer is shortest continous span from the passage.

Example Input: Restless legs syndrome is a neurological disorder characterized by an urgency to move the legs during periods of rest. Data from a variety of sources provide a compelling argument that the amount of iron in the brain is lower in individuals with restless legs syndrome compared with neurologically normal individuals. Moreover, a significant percentage of patients with restless legs syndrome are responsive to intravenous iron therapy. The mechanism underlying the decreased iron concentrations in restless legs syndrome brains is unknown. We hypothesize that the source of the brain iron deficit is at the blood-brain interface. Thus we analysed the expression of iron management proteins in the epithelial cells of the choroid plexus and the brain microvasculature in post-mortem tissues. The choroid plexus, obtained at autopsy, from 18 neurologically normal controls and 14 individuals who had primary restless legs syndrome was subjected to histochemical staining for iron and immunostaining for iron management proteins. Iron and heavy chain ferritin staining was reduced in the epithelial cells of choroid plexus in restless legs syndrome. Divalent metal transporter, ferroportin, transferrin and its receptor were upregulated in the choroid plexus in restless legs syndrome. Microvessels were isolated from the motor cortex of 11 restless legs syndrome and 14 control brains obtained at autopsy and quantitative immunoblot analyses was performed. Expression of heavy chain ferritin, transferrin and its receptor in the microvessels from restless legs syndrome was significantly decreased compared with the controls but divalent metal protein 1, ferroportin, prohepcidin, mitochondrial ferritin and light-chain ferritin remained unchanged. The presence of an iron regulatory protein was demonstrated in the brain microvasculature and the activity of this protein is decreased in restless legs syndrome; a finding similar to our earlier report in neuromelanin cells from the substantia nigra of restless legs syndrome brains. This study reveals that there are alterations in the iron management protein profile in restless legs syndrome compared with controls at the site of blood-brain interface suggesting fundamental differences in brain iron acquisition in individuals with restless legs syndrome. Furthermore, the decrease in transferrin receptor expression in the microvasculature in the presence of relative brain iron deficiency reported in restless legs syndrome brains may underlie the problems associated with brain iron acquisition in restless legs syndrome. The consistent finding of loss of iron regulatory protein activity in restless legs syndrome brain tissue further implicates this protein as a factor in the underlying cause of the iron deficiency in the restless legs syndrome brain. The data herein provide evidence for regulation of iron uptake and storage within brain microvessels that challenge the existing paradigm that the blood-brain barrier is merely a transport system.
Example Output: Which deficiency is the cause of restless leg syndrome?

Example Input: German academics believe they have solved the centuries-old mystery of the "Mona Lisa" in Leonardo ad Vinci's famous portrait . Lisa Gherardini, the wife of a wealthy Florentine merchant, Francesco del Giocondo, has long been seen as the most likely model for the sixteenth-century painting. Art historians have wondered whether the smiling woman may actually have been da Vinci's lover or mother, or the artist himself. Now experts at the prefix = st1 /HeidelbergUniversitylibrary say old notes made in a book by its owner in October, 1503, confirm that Lisa del Giocondo was indeed the model for the famous portrait in the world. "All doubts about the identity of the Mona Lisa have been removed by a discovery by Dr. Armin Schlechter," the library said in a statement on Monday. "Until then, only 'scant evidence' from sixteenth-century documents had been available. These had left lots of room for doubt, and many different identities were put forward." The comments compare Leonardo to the ancient Greek artist Apelles, and say he was working on three paintings at that time, one of which was a portrait of Lisa del Giocondo. Art experts say the Heidelbergdiscovery is a break-through, and the earliest mention linking the merchant's wife to the portrait. Before this discovery the earliest link dated from around 1550, and was made by Italian official Giorgio Vasari, the library said, adding that there had been doubts about Vasari's reliability. The Heidelbergnotes were actually discovered over two year's ago in the library by Schlechter, a spokeswoman said. Although the findings were published in the library's catalogue, they were not widely publicized, and received little attention until a German broadcaster decided to do some recording there, she said.
Example Output: Who discovered the Heidelbergnotes?

Example Input: During the war, the Russian army organized the Crimean campaigns of 1687 and 1689 both which ended in Russian defeats. Despite these setbacks, Russia launched the Azov campaigns in 1695 and 1696, and after raising the siege in 1695 successfully occupied Azov in 1696.
Example Output:
Which campaign was successful?