Question

which meaning of practice fits the way it is used in paragraph 2?
the repeated performance of an activity or skill
a session for learning or improving a skill
a usual way of doing something
the business of a doctor or lawyer

Explanation:

In the context of "Growing green lawns in the desert is a wasteful practice", "practice" refers to a usual way of doing something. The text is criticizing the common (usual) act of growing green lawns in a desert area as it has negative consequences like water waste, etc. The other meanings: "the repeated performance of an activity or skill" (like practicing a sport move repeatedly), "a session for learning or improving a skill" (like a piano practice session), and "the business of a doctor or lawyer" (like a medical practice) do not fit the context of describing the act of growing lawns in a desert.

Answer:

a usual way of doing something