This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.

Input: Consider Input: The Delhi Metro is a rapid transit system serving New Delhi, Delhi, Gurgaon, Faridabad, Noida, and Ghaziabad in the National Capital Region of India. Delhi Metro is the world's 12th largest metro system in terms of length. Delhi Metro was India's first modern public transportation system, which had revolutionised travel by providing a fast, reliable, safe, and comfortable means of transport. The network consists of six lines with a total length of 189.63 kilometres (117.83 miles) with 142 stations, of which 35 are underground, five are at-grade, and the remainder are elevated. All stations have escalators, elevators, and tactile tiles to guide the visually impaired from station entrances to trains. It has a combination of elevated, at-grade, and underground lines, and uses both broad gauge and standard gauge rolling stock. Four types of rolling stock are used: Mitsubishi-ROTEM Broad gauge, Bombardier MOVIA, Mitsubishi-ROTEM Standard gauge, and CAF Beasain Standard gauge.

Output: What is the total length of the Delhi Metro?


Input: Consider Input: Among the notable structures in the town are the three forts built by the Swedes for defense purposes. One of these forts, known as Fort Oscar (formerly Gustav Adolph), which overlooks the sea is located on the far side of La Pointe. However, the ruins have been replaced by a modern military building which now houses the local gendarmerie. The other fort known as Fort Karl now presents a very few ruins. The third fort built by the Swedes is the Fort Gustav, which is also seen in ruins strewn around the weather station and the Light House. The fort built in 1787 over a hill slope has ruins of ramparts, guardhouse, munitions depot, wood-burning oven and so forth.

Output: Who built the three forts on St. Barts?


Input: Consider Input: In 1937 over 100 people died after ingesting "Elixir Sulfanilamide" manufactured by S.E. Massengill Company of Tennessee. The product was formulated in diethylene glycol, a highly toxic solvent that is now widely used as antifreeze. Under the laws extant at that time, prosecution of the manufacturer was possible only under the technicality that the product had been called an "elixir", which literally implied a solution in ethanol. In response to this episode, the U.S. Congress passed the Federal Food, Drug, and Cosmetic Act of 1938, which for the first time required pre-market demonstration of safety before a drug could be sold, and explicitly prohibited false therapeutic claims.


Output: Who manufactured "Elixir Sulfanilamide"?