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).

Paragraph: To reduce friction, oil is added to the engine.
 Question: Jeff should add _____ to his engine to decrease the friction in its processes. 
 Choices: A)oil 
B)gas
gas

Paragraph: At higher concentrations, particles of reactants are crowded closer together, so they are more likely to collide and react.
 Question: Mike is watching how particles of reactants function, and sees that they are very far apart. Considering that the concentration of them is very low, the chance of them colliding together is 
 Choices: A)high 
B)low
low

Paragraph: More advanced farming practices allowed a single farmer to grow food for many more people.
 Question: As fewer computers have made work harder for people we have had to do 
 Choices: A)more work 
B)less work.

more work