instruction:
Given a context passage, generate a question from the passage such that its answer is shortest continous span from the passage.
question:
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.
answer:
Which deficiency is the cause of restless leg syndrome?


question:
The Rebellion was the career highlight for both leaders; Cumberland resigned from the Army in 1757 and died of a stroke in 1765. Charles was initially treated as a hero on his return to Paris but the Stuarts were once again barred from France by the 1748 Treaty of Aix-la-Chapelle. Henry Stuart's entry into the Catholic Church in June 1747 was seen as tacit acceptance the Jacobites were finished and Charles never forgave him. He continued attempts to reignite the cause, including a secret visit to London in 1750 but habitual heavy drinking made him argumentative and hard to work with. In 1759, he met French Chief Minister de Choiseul to discuss another invasion attempt but Choiseul dismissed him as incapable through drink. When his father James died in 1766, Pope Clement XIII refused to recognise him as Charles III, despite the strong objections of his brother Henry. Charles never visited Britain again and died in Rome in January 1788, a disappointed and embittered man.
answer:
Which happened first, Charles secret visit to London or his meeting with French Chief Minister de Choiseul?


question:
When the series was revisited for the 10 year anniversary, both Northstar and Aurora are later killed by Weapon X (Wolverine) and Kirika (X-23 in the main Marvel Universe).
answer:

Which fictional universe is Northstar from?