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).
One example: Paragraph: Many of the worlds people live with water scarcity, and that percentage will increase as populations increase and climate changes.
 Question: John's town used to have lots of water, back when there were only a few hundred people. However, now that the town holds several thousand people, the water availability is 
 Choices: A)scarce 
B)plentiful
Solution is here: scarce
Explanation: Based on the information given in the paragraph, population growth will make water more scarce, so that is the correct answer.

Now, solve this: Paragraph: At higher concentrations, particles of reactants are crowded closer together, so they are more likely to collide and react.
 Question: DJ has a solution that he adds particles to. The solution is now a _____ concentration. 
 Choices: A)higher 
B)lower
Solution:
higher