This task is about writing a correct answer for the reading comprehension task. Based on the information provided in a given passage, you should identify the shortest continuous text span from the passage that serves as an answer to the given question. Avoid answers that are incorrect or provides incomplete justification for the question.

Example Input: Passage: Maximilian was deeply dissatisfied with General Bazaine's decision to abandon the state capital of Chihuahua and immediately ordered Agustín B. Billaut to recapture the city. On December 11, 1865, Billaut with a force of 500 men took control of the city. By January 31, 1866 Billaut was ordered to leave Chihuahua, but he left behind 500 men to maintain control. At the zenith of their power, the imperialist forces controlled all but four states in Mexico; the only states to maintain strong opposition to the French were: Guerrero, Chihuahua, Sonora, and Baja California. Question: In which year did Billaut capture Chihuahua?
Example Output: 1865

Example Input: Passage: In the city, the population was spread out with 21.9% at age 19 and under, 14.3% from 20 to 24, 33.2% from 25 to 44, 20.4% from 45 to 64, and 10.1% who were 65 years of age or older. The median age was 30.8 years. For every 100 females, there were 92.0 males. For every 100 females age 18 and over, there were 89.9 males. There were 252,699 households, of which 20.4% had children under the age of 18 living in them, 25.5% were married couples living together, 16.3% had a female householder with no husband present, and 54.0% were non-families. 37.1% of all households were made up of individuals and 9.0% had someone living alone who was 65 years of age or older. The average household size was 2.26 and the average family size was 3.08. Question: What percentage of the City of Boston's residents are over 65?
Example Output: 10.1%

Example Input: Passage: During the years 1940-1955, the rate of decline in the U.S. death rate accelerated from 2% per year to 8% per year, then returned to the historical rate of 2% per year. The dramatic decline in the immediate post-war years has been attributed to the rapid development of new treatments and vaccines for infectious disease that occurred during these years. Vaccine development continued to accelerate, with the most notable achievement of the period being Jonas Salk's 1954 development of the polio vaccine under the funding of the non-profit National Foundation for Infantile Paralysis. The vaccine process was never patented, but was instead given to pharmaceutical companies to manufacture as a low-cost generic. In 1960 Maurice Hilleman of Merck Sharp & Dohme identified the SV40 virus, which was later shown to cause tumors in many mammalian species. It was later determined that SV40 was present as a contaminant in polio vaccine lots that had been administered to 90% of the children in the United States. The contamination appears to have originated both in the original cell stock and in monkey tissue used for production. In 2004 the United States Cancer Institute announced that it had concluded that SV40 is not associated with cancer in people. Question: Who created the polio vaccine?
Example Output:
Jonas Salk