Edgar Guest is an American poet, famous for his optimistic tone. He was also called People's Poet.
A hero is defined as someone who is valuable or appreciated by his achievements or good qualities or by his courage.
In the third option, the speaker contrasts two different groups: first one is described in line 3 of the excerpt ("Are you one...?") and the characteristics of the other group are defined in the other lines (The things that...) and the final line adds emphasis by asking a direct question. The semantic field is also related in the statement and in the excerpt (uncharted, new discoveries, path and undone things, lead, way), making the third option the right answer.
The rise in respiratory diseases like allergies and asthma is probably due to changes in climatic conditions globally. The climate changes trigger and disturb the harmonized levels of air borne particles and thus increasing their numbers which is causing air pollution and ultimately affecting people. Moreover, the excessive use of energy-proofing of work places and indoors and use of antibiotics have increased the rates of susceptibility to infections.
