1. Use of infinitive of purpose: "mainly for relaxation and stress relief" uses the preposition "for" followed by nouns to explain the purpose of walking in parks.
2. Use of relative clause: "which helps people unwind and forget about their worries" uses "which" to introduce a relative clause, adding detail about why parks are beneficial.
3. Present simple tense: The answer consistently uses the present simple tense ("enjoy," "are," "helps," "can improve," "making") to describe general truths and habits.