What is a "filter bubble?"

Plz change it i can not change this sentences .

Baca use comforting imagery. which lines have a more serious tone than the rest of the poem a. when the outside world / no longer cares if you live or die; b. so it is a pot full of yellow corn / to warm your belly in winter, c. remember. / i love you.d. it's all i have to give, / and all anyone needs to live,

What were the strengths used to persuade the audience in the speech “i have a dream” i really need on this one. i also posted a few more. can someone ?