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: 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?
51st

Passage: Lafayette Park is a revitalized neighborhood on the city's east side, part of the Ludwig Mies van der Rohe residential district. The 78-acre (32 ha) development was originally called the Gratiot Park. Planned by Mies van der Rohe, Ludwig Hilberseimer and Alfred Caldwell it includes a landscaped, 19-acre (7.7 ha) park with no through traffic, in which these and other low-rise apartment buildings are situated. Immigrants have contributed to the city's neighborhood revitalization, especially in southwest Detroit. Southwest Detroit has experienced a thriving economy in recent years, as evidenced by new housing, increased business openings and the recently opened Mexicantown International Welcome Center. Question: What district is Lafayette Park a part of?
Ludwig Mies van der Rohe residential district

Passage: Buses now provide the majority of local public transport. The main bus operators are First Southampton and Bluestar. Other operators include Brijan Tours, Stagecoach and Xelabus. The other large service provider is the Uni-link bus service (running from early in the morning to midnight), which was commissioned by the University of Southampton to provide transport from the university to the town. Previously run by Enterprise, it is now run by Bluestar. Free buses are provided by City-link'. The City-link runs from the Red Funnel ferry terminal at Town Quay to Central station via WestQuay and is operated by Bluestar. There is also a door-to-door minibus service called Southampton Dial a Ride, for residents who cannot access public transport. This is funded by the council and operated by SCA Support Services. Question: What time does Uni-link stop service to the university each night?

midnight

