题目内容：

    It's common knowledge that the woman in Leonardo da Vinci's most famous painting seems to look back at observers, following them with her eyes no matter where they stand in the room. But this common knowledge turns out wrong.

A new study finds that the woman in the painting is actually looking out at an angle that's 15.4 degrees off to the observer's right—well outside of the range that people normally believe when they think someone is looking right at them. In other words, said the study author, Horstmann, ''She's not looking at you. '' This is somewhat ironic, because the entire phenomenon of a person's gaze (凝视) in a photograph or painting seeming to follow the viewer is called the ''Mona Lisa effect''. That effect is absolutely real, Horstmann said. If a person is illustrated or photographed looking straight ahead, even people viewing the portrait from an angle will feel they are being looked at. As long as the angle of the person’s gaze is no more than about 5 degrees off to either side, the Mona Lisa effect occurs.

Horstmann and his co-author were studying this effect for its application in the creation of artificial-intelligence avatars(虚拟头像) when Horstmann took a long look at the ''Mona Lisa'' and realized she wasn't looking at him. To make sure it wasn't just him, the researchers asked 24 people to view images of the ''Mona Lisa'' on a computer screen.

So why do people repeat the belief that her eyes seem to follow the viewer? Horstmann isn't sure. It's possible, he said, that people have the desire to be looked at, so they think the woman is looking straight at them. Or maybe the people who first coined the term ''Mona Lisa effect'' just thought it was a cool name.

1.What is generally believed about the woman in the painting ''Mona Lisa''?

A.She attracts the viewers to look back.

B.She seems mysterious because of her eyes.

C.She fixes her eyes on the back of the viewers.

D.She looks at the viewers wherever they stand.

2.What gaze range in a painting will cause the Mona Lisa effect?

A. B.

C. D.

3.Why was the experiment involving 24 people conducted?

A.To confirm Horstmann's belief.

B.To create artificial-intelligence avatars.

C.To calculate the angle of Mona Lisa's gaze.

D.To explain how the Mona Lisa effect can be applied.

4.What can we learn from the text?

A.Horstmann thinks it's cool to coin the term “Mona Lisa effect”.

B.The Mona Lisa effect contributes to the creation of artificial intelligence.

C.Feeling being gazed at by Mona Lisa may be caused by the desire for attention.

D.The position of the ruler in the experiment will influence the viewers' judgment.