President Barack Obama had a big pat on the back for his young daughters on Tuesday, saying they have got used to life in the White House.

After more than a year at the US presidential mansion, Malia Obama, 11, and Sasha Obama, 8, have made their dad proud with their ability to balance their private life with life in the public eye, he told NBC television.
"The happiest thing about the past year and a half has been the girls' adjustment (适应). They have just been great. They're doing well in school," Obama said.
"They're not as constrained. They can wander around. Their Secret Service protection is a lot more low key (低调)," he explained. "So they've got soccer, they've got basketball, they go sleep over at their friend's houses.
"Sometimes I've got 12 little girls screaming on the third floor of the White House. And they made a great adjustment."
The president also admitted he was concerned about how his daughters would deal with his public life as they get a bit older.
"Now I get a little worried about them when they're teenagers because I think that's the time when you're already feeling uncomfortable about your parents, and then imagine if your dad's in the newspaper every day and people are calling him a fool. I feel a little worried about that."
"But on the other hand, Malia and Sasha have just turned out to be unbelievably well adjusted kids," Obama said.
"The thing that's most important to me is that they are so respectful of everybody and haven't gotten on any airs (摆架子). It’s all because of Michelle as she wouldn't put up with (容忍) any of that stuff."
Why is President Obama so happy according to the passage?

A．His daughters have been great in the public eye.

B．His daughters can balance their life with their study.

C．His daughters have got used to life in the White House.

D．His daughters have been in the White House for over a year.

The underlined word “constrained” in Paragraph 4 most probably means__________.

A．devoted B．forced C．puzzled D．concerned

President Obama is a little worried about ___________.

A．what his daughters’ life will be like in the future

B．how his daughters will get on with him when they’re a little older

C．how his daughters will make friends with people around in the future

D．how his daughters will deal with his public life when they’re teenagers

What can we infer from the last paragraph?
A. Michelle is proud of being Obama’s wife.
B. Michelle allows her daughters to get on airs.
C. President Obama appreciates what Michelle has done.
D. Obama’s daughters are respected by everyone in the USA.