Name the vitamin required for making bones and teeth strong

calcium

Explanation:

Throughout the body, the mineral helps build bones and provide structural support. In your mouth, calcium helps harden your enamel and strengthen your jawbone.

a. "to practice" is the best phrase to complete the sentence.

explanation:

during the summer, she likes to practice her soccer skills so that she is ready to play in the fall.

(note that : all the other options "the practicing of", "practice for" and "to do a practice on" are inappropriate as they make the sentence grammatically incorrect.)