"I, Too" is a poem written by Langston Hughes that was first published in 1925. In order to help you decide which line best sums up the main theme of the poem, it is important to consider what the main theme of the poem is. The main theme of this poem is clearly racial inequality, as the poet shows us how life feels for an oppressed Black American. Looking at the poem from this angle, the line that best sums up this theme would be the line "They send me to eat in the kitchen." This line shows the reader how Black Americans were treated as inferior human beings—how they had to be hidden away somewhere, as they were not deemed to be suitable company.

However, there is also another angle from which the main theme is shown in this poem. The poem is not merely describing racial discrimination and oppression. Instead, the poem also illustrates the hope and desire of Black people to be treated equally and with respect by their fellow White citizens. In this instance, you might want to argue that the line "I, too, am America" highlights the poet's hope that one day, there will be one undivided America, where both White and Black people will live together in peace and harmony.