Which situation would require a leader to initiate discussion in a group discussion

well there are a bunch of different possibilities so your gonna have to be a bit more specific

direct attacks on us ships

germany’s attempted alliance with mexico

a desire to preserve democracy in the world

"urban sprawl, the spreading of large developments of housing and shopping areas around a city’s center, has many negative cultural and environmental effects. " (from your link)

so, your answer is: it has a negative effect on the environment, otherwise known as c~hope this mate.