Son anniversaire est le 12 décembre.
The answer is in the sentence: "En hiver, c'est mon anniversaire le douze decémbre." which translates to "In winter, it is my birthday on the 12th of december.
If only i could actually read this
Tu bois du lait is the right answer
Tu bois de l’eau would be the right answer if it was " lait " instead of " eau "
(lait means milk and eau means water)
Tu boivent de l’eau, tu boivent du lait are not correct at all, you can forget these two