You are given a background paragraph that describes one or more causal or qualitative relationships such as a relationship in economics or a scientific law and a story that makes use of the concepts or the relationship described in the provided paragraph. You are also given a question about the story that requires an understanding of the relationship described in the background paragraph and the story. You need to come up with an answer to the given question; the answer will be a span from either the question or the story. In order to correctly answer the given question, you need to understand the relationship mentioned in the background paragraph and should be able to use it to understand that in the story. Your answer can not consist of any word that is not mentioned in any of these: the background paragraph, the story, or the question. You can directly copy and paste a span from the story or the question while answering the given question.

Input: Consider Input: Background Paragraph: The classical explanation of gravity is that a force of attraction acts at a distance between two objects and the magnitude of the force is directly proportional to each of the masses and inversely proportional to the square of the distance between the objects. The objects move toward each other due to this force of attraction. Einstein’s new concept of gravity states that matter (mass) causes the space around the matter to curve and also distorts time. A straight line through this curved space would also be curved in order to be a straight line. 
Story: Rob is an amateur astronomer. Recently, he detected four asteroids, asteroid A, asteroid B, asteroid C, and asteroid D. Asteroid A and asteroid B are of the same mass, but asteroid A is farther from the earth than asteroid B. Asteroid C and asteroid D are at the same distance form the earth, but asteroid C has more mass than asteroid D. He also figured out that all of these asteroids have less mass than earth. 
Question: In clssical theory, if Rob needs to find out the object with stronger gravitational pull, which one would he choose, earth or asteroid A?

Output: earth.


Input: Consider Input: Background Paragraph: Extending the period of time over which a force acts in order to lessen the force is a common practice in design. Padding in shoes and seats allows the time to increase. The front of automobiles are designed to crumple in an accident; this increases the time the car takes to stop. Similarly, barrels of water or sand in front of abutments on the highway and airbags serve to slow down the stoppage time. These changes all serve to decrease the amount of force it takes to stop the momentum in a car crash, which consequently saves lives. 
Story: Keith designs car seats. He noticed that some other car seats didn't have any padding. He marked it as case A. On the other hand, most of the seats he designed had padding. He marked it as case B. Keith needed to know pros and cons of both designs. 
Question: Which case would more likely make products unsafe, case A or case B?

Output: case A.


Input: Consider Input: Background Paragraph: Alkali, or Alkaline, soils are clay soils with high pH (> 8.5), a poor soil structure and a low infiltration capacity. Often they have a hard calcareous layer at 0.5 to 1 metre depth. Alkali soils owe their unfavorable physico-chemical properties mainly to the dominating presence of sodium carbonate, which causes the soil to swell[1] and difficult to clarify/settle. They derive their name from the alkali metal group of elements, to which sodium belongs, and which can induce basicity. Sometimes these soils are also referred to as alkaline sodic soils.
Alkaline soils are basic, but not all basic soils are alkaline. 
Story: Two brothers have a piece of land each, situated 2 miles from each other. Jim's land is not very fertile because it has clay soil with a high pH, while Bob's land has very fertile soil and has a good productivity on it. 
Question: Which of the two pieces of land is more fertile?


Output: Bob's.