Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 31 to 35.

The Japanese love inventing and they are very good at it. But there is one inventor who has invented more things than anyone else in Japan-Dr. Nakamats. He has designed over 4,000 new inventions over the last fifty years. He is most well-known for his unusual inventions.

He designed many strange things such as glasses which look like eyes so you can't notice them, shoes which have steel springs so that you can jump in them, and a pillow which stops you from falling asleep when you are driving.

How does he come up with these ideas? He finds listening to Beethoven helpful. But the thing that makes him most creative is holding his breath underwater. He dives into his swimming pool every day and stays underwater as long as he can. He believes that less oxygen in the brain is good for new ideas. He also dives with a pencil and a notebook which he invented. He needs to write down his ideas immediately in the water because they disappear quickly.

Dr. Nakamats believes that eating the right food is important for creativity, and he has invented some snacks that he says are good for your brain. He has also invented an armchair which helps to enhance your brainpower. He sits in the chair every day to give him more good ideas. Dr. Nakamats is now in his eighties, but he plans to live until he is 144 years old, so he still has plenty of time to develop even more new ideas.

(Adapted from Get Ahead)

The word "enhance" in paragraph 4 is closest in meaning to