Final answer:
The line from the poem refers to the speaker's entire physical self, with an emphasis on blood and being formed from the environment. None of the multiple-choice options (Heart, Lungs, Skin, Brain) is directly mentioned in the poem, but 'Lungs' could be closely associated due to the mention of 'air'.
Step-by-step explanation:
The poetic expression "My tongue, every atom of my blood, form’d from this soil, this air" refers to the physical body, with an emphasis on the blood and its connection to the land and air of the speaker's birthplace. It demonstrates a deep connection to the environment, where the speaker feels that every part of their being, including their blood and tongue, is formed from the physical elements of their homeland. However, to answer the multiple-choice question, none of the provided options is directly mentioned in the line from the poem. The closest association can be made with the lungs, which are responsible for taking in the air, but the question seems to contain a misunderstanding of the text as none of the choices accurately fits the description provided in the poetic line.