one goal of america recycles day is to raise awareness of the growing landfill problem.which of these phrases is the complete infinitive phrase in the sentence? of the growing landfill problem
to raise awareness of the growing landfill problem
of america recycles day
to raise awareness

The correct answer should be
to raise awareness of the growing landfill problem

The infinitive phrase is to raise awareness because that's the infinitive (to raise) and the noun (awareness). However, of the growing landfill problem is also there because the complete infinitival phrase means that there's the infinitive and all other complements and modifiers that modify it.