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.

Ex Input:
Passage: Uranium is a naturally occurring element that can be found in low levels within all rock, soil, and water. Uranium is the 51st element in order of abundance in the Earth's crust. Uranium is also the highest-numbered element to be found naturally in significant quantities on Earth and is almost always found combined with other elements. Along with all elements having atomic weights higher than that of iron, it is only naturally formed in supernovae. The decay of uranium, thorium, and potassium-40 in the Earth's mantle is thought to be the main source of heat that keeps the outer core liquid and drives mantle convection, which in turn drives plate tectonics. Question: Where does uranium rank among elements in terms of its abundance in the Earth's crust?

Ex Output:
51st

Ex Input:
Passage: At a convention of citizens called to select a new provisional ruler, Gutierrez obtained the vote, with P. J. Escalante for his deputy, and a council to guide the administration. Santa Anna ordered the reinstatement of Mendarozqueta as comandante general. Gutierrez yielded, but Escalante refused to surrender office, demonstrations of support ensued, but Escalante yielded when troops were summoned from Zacatecas. A new election brought a new legislature, and conforming governors. In September 1835 Jose Urrea a federalist army officer came into power. Question: Who was his deputy?

Ex Output:
P. J. Escalante

Ex Input:
Passage: Roughly one quarter of all zinc output in the United States (2009), is consumed in the form of zinc compounds; a variety of which are used industrially. Zinc oxide is widely used as a white pigment in paints, and as a catalyst in the manufacture of rubber. It is also used as a heat disperser for the rubber and acts to protect its polymers from ultraviolet radiation (the same UV protection is conferred to plastics containing zinc oxide). The semiconductor properties of zinc oxide make it useful in varistors and photocopying products. The zinc zinc-oxide cycle is a two step thermochemical process based on zinc and zinc oxide for hydrogen production. Question: Why is zinc oxide useful in photocopying products?

Ex Output:
semiconductor