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

Example Input: Iron deficiency is the most common nutritional disorder affecting at least one third of world's population. Though anemia is common manifestation of iron deficiency, other effects of iron deficiency on various tissues, organs and systems are usually under recognized. Impaired brain development and cognitive, behavioural and psychomotor impairment are most worrisome manifestations of iron deficiency. Studies have demonstrated that some of these changes occurring during period of brain growth spurt (<2 years age) may be irreversible. Association of iron deficiency with febrile seizures, pica, breath holding spells, restless leg syndrome and thrombosis is increasingly being recognized. Impaired cell-mediated immunity and bactericidal function are generally noted in iron-deficient persons; however, the findings are inconsistent. Despite proven reversible functional immunological defects in vitro studies, a clinically important relationship between states of iron deficiency and susceptibility to infections remains controversial. Studies from malaria endemic regions have reported increased incidence of malaria in association with iron supplementation. These and some other aspects of iron deficiency are reviewed in this article.
Example Output: Which deficiency is the cause of restless leg syndrome?

Example Input: The Rose Experience is the fourth studio album by multi-platinum R&B singer Case.
Example Output: What is the name of the artist or group which originally performed The Rose Experience?

Example Input: The Gruffalo is a children's book by writer and playwright Julia Donaldson, illustrated by Axel Scheffler, that tells the story of a mouse, the protagonist of the book, taking a walk in a European forest.
Example Output:
What person illustrated The Gruffalo?