Given a context passage, generate a question from the passage such that its answer is shortest continous span from the passage.
Example: In 1582 the united provinces invited francis, duke of anjou to lead them; but after a failed attempt to take antwerp in 1583, the duke left the netherlands again. after the assassination of william of orange (10 july 1584), both henry iii of france and elizabeth i of england declined the offer of sovereignty. however, the latter agreed to turn the united provinces into a protectorate of england (treaty of nonsuch, 1585), and sent the earl of leicester as governor-general. this was unsuccessful and in 1588 the provinces became a confederacy. the union of utrecht is regarded as the foundation of the republic of the seven united provinces, which was not recognized by the spanish empire until the peace of westphalia in 1648.
Example solution: In what year did francis, duke of anjou leave the netherlands?
Example explanation: The generated question is perfect. Because the question is based on second sentence of the input passage and its answer is 1583.

Problem: New software is able to analyze exactly how many hairs there are in a patch of skin and could help in testing the effectiveness of baldness treatments and depilatory creams, say Australian researchers. Researchers from CSIRO Mathematical and Information Sciences in prefix = st1 /Sydneyreport their findings in the November issue of the journalSkin Research and Technology. The software, developed with a UKcompany, will make it easier for researchers developing hair removal creams to accurately assess how well they work, says Dr Pascal Vallotton. "Up to now they were counting the number of hairs that survived after treatment by hand. That's hard work and it's difficult because you may count a hair twice or you may miss it." he said. The software relies on images captured by a small flatbed scanner pressed onto the skin. Using a mathematical algorithm , the software then identifies and traces each individual hair based on an understanding of a hair's unique features, such as its straightness. The software is able to distinguish between hairs and other features on the skin such as wounds or moles . "Our skin irregularities make it difficult to say this is a hair or this is a mole," Dr Vallotton said. Comparison between earlier and later images can also determine if hair is growing quickly or slowly, he says. Unfortunately, to check the accuracy of the software, the researchers still had to adopt the old-fashioned method of counting hairs, helped by volunteers from neighboring labs who put their skins on the line for science. "We had 12 volunteers, mostly from neighboring labs, and we acquired images of hair before and after treatment," Dr Vallotton said. To ensure an accurate count, the individual hairs had to be marked off as they were counted, but after such a laborious process, the researchers were pleased to discover the software results were comparable to the manual count. Dr Vallotton says the software could also be useful in testing the effectiveness of balding treatments and counting or tracing substances other than hairs, that are long and thin and otherwise difficult to image.

Solution: What plays a key role in counting the number of hairs with the software?