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.

Passage: Naturally occurring glass, especially the volcanic glass obsidian, has been used by many Stone Age societies across the globe for the production of sharp cutting tools and, due to its limited source areas, was extensively traded. But in general, archaeological evidence suggests that the first true glass was made in coastal north Syria, Mesopotamia or ancient Egypt. The earliest known glass objects, of the mid third millennium BCE, were beads, perhaps initially created as accidental by-products of metal-working (slags) or during the production of faience, a pre-glass vitreous material made by a process similar to glazing. Question: What was obsidian used to make in prehistoric times?
cutting tools

Passage: The Wagner tuba, a modified member of the horn family, appears in Richard Wagner's cycle Der Ring des Nibelungen and several other works by Strauss, Béla Bartók, and others; it has a prominent role in Anton Bruckner's Symphony No. 7 in E Major. Cornets appear in Pyotr Ilyich Tchaikovsky's ballet Swan Lake, Claude Debussy's La Mer, and several orchestral works by Hector Berlioz. Unless these instruments are played by members doubling on another instrument (for example, a trombone player changing to euphonium for a certain passage), orchestras will use freelance musicians to augment their regular rosters. Question: What is the name of the modified member of the horn family appearing in several works by Strauss?
The Wagner tuba

Passage: The wastewater treatment plant and distribution system of water mains, pumping stations and storage facilities provide water to approximately 62,000 customers in the city. There is also a wastewater treatment plant located on the south bank of the James River. This plant can treat up to 70 million gallons of water per day of sanitary sewage and stormwater before returning it to the river. The wastewater utility also operates and maintains 1,500 miles (2,400 km) of sanitary sewer and pumping stations, 38 miles (61 km) of intercepting sewer lines, and the Shockoe Retention Basin, a 44-million-gallon stormwater reservoir used during heavy rains. Question: How much water is contained in Shockoe Retention Basin?

44-million-gallon