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: For a given medium, sound has a slower speed at lower temperatures.
 Question: If Jim turns the thermostat down in his room while listening to music, what will happen to the speed of the sound waves in the room? 
 Choices: A)they will speed up 
B)they will slow down
[EX A]: they will slow down

[EX Q]: Paragraph: If there are more greenhouse gases in the atmosphere, more ultraviolet radiation will be trapped and the Earth will heat up.
 Question: Carl is studying climate change, and notes that less ultraviolet radiation is being trapped, which means the earth will be 
 Choices: A)cooler 
B)warmer
[EX A]: cooler

[EX Q]: Paragraph: By using multiple stages, empty fuel containers could drop away. This reduced the mass of the rocket so that it could fly higher.
 Question: David is getting ready to fly into space on a rocket. As the rocket shoots upwards, part of the mass falls away, allowing the rocket to go 
 Choices: A)higher 
B)lower
[EX A]:
higher