The apple tree may be one of the oldest fruit trees in the world.There is evidence of people eating apples all the way back in the Stone Age.This sweet-tasting,healthy fruit is still a favorite among people everywhere.More than 60 million tons of apples are eaten worldwide each year.
Now there may be good news for apple lovers.Soon they may be even crunchier(香脆) and juicier.Scientists have now mapped the genome of the Golden Delicious apple.A global team of 86 scientists from Italy,France,New Zealand,Belgium,and the US spent two years on the work.Professor Riccardo Velasco in Italy,who led the research team,said that mapping the genome would have a big effect on apple breeding(培育).“This breakthrough will help us to develop high quality traits and bring new things to the apple market,” he told BBC News.
Scientists hope improvements to the popular Golden Delicious apple,which began to grow in the US more than a century ago,could make the fruit look and taste better.The decoding of the apple’s DNA also tells us more about its beginning.The researchers traced the fruit back to Malus sieversii,a wild plant that grew in the mountains of southern Kazakhstan about 4000 years ago.There are more than 7,500 varieties of apple known today.
The team now wants to find more of the apple’s secrets,such as which genes control flavor.Looking through all the information takes time.Scientists turned to some of the apple’s relatives,pears,peaches,and grapes,to help them finish their job.Even though these fruits look and taste different,they share some genes.“Knowing how a gene in a peach works sheds light on how a similar gene may work in an apple,” said Amit Dhingra from Washington State University,one of the researchers.“It also helps us identify what genes are unique to each fruit.”
Which of the following statements is TRUE of apples?

A．Apples are considered healthy food.

B．Apples have been eaten for millions of years.

C．Apples don’t vary much in different parts of the world.

D．Apples share exactly the same genes with pears and grapes.

The researchers on the global team are trying to improve the quality of apples by  .

A．cross-breeding

B．creating new DNA

C．studying their genes

D．finding new varieties

What does the underlined phrase“sheds light on”mean?

A．Brings light to.

B．Tests out on.

C．Helps to explain.

D．Throws doubts on.

The main point of the passage is that    .

A．even apples have secrets

B．scientists have mapped the DNA of apples

C．scientists can make apples tastier

D．apples are so popular because of their flavor