阅读下面短文，从各题A、B、C、D四个选项中，选出最佳选项。
Your brain isn’t a muscle, but you can treat it like one
Many people focus on physical fitness, but few know that brain fitness is also something you can work on. In fact, you can exercise your brain as often as you do to your arms or legs —and the results can be positive and empowering.
To improve your brain, you can’t simply repeat the same exercises over and over. Just as lifting a two—pound weight will stop challenging you, so will repetitive exercises such as crosswords or Sudoku. Once you master easy exercises, you must move on to harder ones in order to push your brain —like your muscles —to a new level.

The science behind brain training
Scientists once believed that your mental abilities were fixed in adulthood. Since studies have shown just the opposite, millions of people around the world have adopted the new practice of brain training. The most popular of these brain training products is made by the San Francisco—based Lumosity. Lumosity's scientists with an experienced team of game designers have developed a fun，effective online brain training program that measures，tracks，and adapts to your progress，so you'll always be challenged.
Promising studies on the effects of brain training
In a 2013 Stanford study，a treatment group of 21 breast cancer survivors used 12 weeks of Lumosity training to work on processing speed，mental flexibility，and working memory tasks. On average，those who trained improved on tests of these abilities，compared to a group that did not train with Lumosity.
There is even some evidence suggesting that Lumosity may be beneficial to normal，healthy adults. In a 2011 study by Lumosity and San Francisco State University researchers. 13 people who trained over 5 weeks improved working memory scores by 10％and attention scores by 20％.
Brain training is designed to meet real-life needs
The design of brain training is targeted at real-life benefits instead of improving game scores. Better attention，for example，can mean greater focus in the classroom or at an important business meeting. With improved processing speed，you might react and adapt faster to the demands of a busy life. And a better memory could mean stronger，longer relationships with the people closest to you.
We can learn from the passage that _________.

A．brain training speeds up the recovery of breast cancer

B．your brain is like a muscle because it gives you power

C．people's mental abilities can't develop after they grow up

D．Lumosity can measure，track and suit your level as you improve

Which skill may brain training not improve?

A．Better attention.	B．A better memory.
C．Better writing skills.	D．Higher processing speed.

What can we infer from the passage?

A．People should care more about physical health instead of mental health.

B．Brain training has been proved effective through scientific researches.

C．A bad memory is the only reason for weak relationships with people.

D．Playing online games is the best way of brain training.

What's the best title for the passage?

A．Brain Training Makes a Difference	B．Train Your Brain like a Muscle
C．Lumosity，Your Best Choice	D．How to Train Your Brain