You are given a short paragraph, a question and two choices to answer from. Choose the correct answer based on the paragraph and write the answer(not the key).

[EX Q]: Paragraph: Warm air is less dense than cool air, so it rises higher in the troposphere.
 Question: If Jim raises the temperature of the air inside his balloon, will his balloon rise higher into the air or sink towards the ground? 
 Choices: A)rise higher 
B)sink lower
[EX A]: rise higher

[EX Q]: Paragraph: When a person exercises regularly, and is fit, the heart undergoes certain long-term adaptations. The heart muscle gets stronger, and expels more blood with each contraction.
 Question: Compared to an obese person who has never exercised, would an Olympic sprinter in perfect condition be more likely to have a heart that can, with each beat, move 
 Choices: A)more blood 
B)less blood?
[EX A]: more blood

[EX Q]: Paragraph: For a given medium, sound has a slower speed at lower temperatures.
 Question: If Mary is playing music in her room and the heater stops working, causing the temperature to fall, what happens to the speed of the soundwaves her radio is generating? 
 Choices: A)increases 
B)decreases
[EX A]:
decreases