Which of the following are the natural barriers that help keep infection out?

Read the poem from "my brothers’ flying machine: orville, wilbur, and me" by jane yolen first before answering these questions. part a: how do lines 1–23 most support a theme of the poem? question 1 options: a by describing how heavy the constructed plane would be b by detailing the commitment that went into the first flight c by showing how tunnels were used to make test flights d by illustrating the challenges of fueling the plane read the poem from "my brothers’ flying machine: orville, wilbur, and me" by jane yolen first before answering these questions. part b which evidence from the poem best supports the answer to part a (question 1)? question 2 options: a “now they worked dawn to dusk / so absorbed in what they were doing,” (lines 1–2) b “they learned about lift and drag.” (line 9) c “gasoline was gravity-fed into the engine” (line 19) d “over six hundred pounds of aeroplane— / it could not be assembled whole in our shop.” (lines 22–23)