Which is the adjective phrase in the sentence?

especially with suburban sprawl, trolleys are a better substitute for smelly buses.

a.
for smelly buses

b.
with suburban sprawl

c.
a better substitute

i think its a
can you explain what you think and why?

Modernist poetry explored the problem that arose from rapid urbanization and industrialization in the late 1800 and early 1900. which two lines in this excerpt from "the anecdote jar" by wallace stevens reflect the themes of barrenness and emptiness of modern life