Maltose contains how many oxygen atoms?

Mutarotation involves -

Observe the following statements.
$I$. Sucrose has glycosidic linkage.
$II$. Cellulose is present in both plants and animals.
$III$. Lactose contains $D$-galactose and $D$-glucose units.
Which of the following statements are correct?

Which carbon atoms of fructose are bonded together through oxygen forming fructofuranose?

What is invert sugar?

The correct statement$(s)$ about the following sugars $X$ and $Y$ is(are):
$(A)$ $X$ is a reducing sugar and $Y$ is a non-reducing sugar
$(B)$ $X$ is a non-reducing sugar and $Y$ is a reducing sugar
$(C)$ The glycosidic linkages in $X$ and $Y$ are $\alpha$ and $\beta$,respectively
$(D)$ The glycosidic linkages in $X$ and $Y$ are $\beta$ and $\alpha$,respectively