What might people do to preserve the sanctity of a special place?

Implementation of a set of regulations and a means to enforce them could be a method to submit people into paying respects while within the bounds a sacred place.

Setting up symbols of sanctity to mark these bounds would also influence people's minds into behaving once passing these limits. A Japense Torii is a good example of these symbols.

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.)