Teacher: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).
Teacher: Now, understand the problem? Solve this instance: Paragraph: Warm air is less dense than cool air, so it rises higher in the troposphere.
 Question: If air warms, it becomes _____ dense. 
 Choices: A)less 
B)more
Student:
less