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: The softness of copper partly explains its high electrical conductivity (59.6×106 S/m) and thus also high thermal conductivity, which are the second highest (to silver) among pure metals at room temperature. This is because the resistivity to electron transport in metals at room temperature mostly originates from scattering of electrons on thermal vibrations of the lattice, which are relatively weak for a soft metal. The maximum permissible current density of copper in open air is approximately 3.1×106 A/m2 of cross-sectional area, above which it begins to heat excessively. As with other metals, if copper is placed against another metal, galvanic corrosion will occur. Question: What is the explanation for copper's capacity for electrical conductivity?
Example Output: The softness

Example Input: Passage: First recognized in 1900 by Max Planck, it was originally the proportionality constant between the minimal increment of energy, E, of a hypothetical electrically charged oscillator in a cavity that contained black body radiation, and the frequency, f, of its associated electromagnetic wave. In 1905 the value E, the minimal energy increment of a hypothetical oscillator, was theoretically associated by Einstein with a "quantum" or minimal element of the energy of the electromagnetic wave itself. The light quantum behaved in some respects as an electrically neutral particle, as opposed to an electromagnetic wave. It was eventually called the photon. Question: Who discovered an association between the value E and quantum energy?
Example Output: Einstein

Example Input: Passage: In August, the couple attended the 2011 MTV Video Music Awards, at which Beyoncé performed "Love on Top" and started the performance saying "Tonight I want you to stand up on your feet, I want you to feel the love that's growing inside of me". At the end of the performance, she dropped her microphone, unbuttoned her blazer and rubbed her stomach, confirming her pregnancy she had alluded to earlier in the evening. Her appearance helped that year's MTV Video Music Awards become the most-watched broadcast in MTV history, pulling in 12.4 million viewers; the announcement was listed in Guinness World Records for "most tweets per second recorded for a single event" on Twitter, receiving 8,868 tweets per second and "Beyonce pregnant" was the most Googled term the week of August 29, 2011. Question: What song did she perform at the MTV Awards?
Example Output:
Love on Top