1. /u u/ u/ u/ u/, u/ u/ // u/ u/
D is the best option for this. One way to easily identify D as the best choice is line 2. The words knock, breathe, shine, seek are all one stressed syllable words (and is unstressed). This shows that you need an option that has 3 stressed syllables followed by an unstressed and stressed syllable.
2. to allow to enter, to claim belief in
In the lines the speaker is saying that he labors to admit the person he is speaking to. In this line labor means to work hard. This eliminates work hard as an option as a meaning for admit because you wouldn't write work hard twice in a row. It's also not to show allegiance - it doesn't fit. Admit does mean to admit. Unfortunately the speaker can't allow the person to enter. The other possible meaning is claim belief in because the speaker can work hard to claim belief in something but not be able to.