Answer: I would contend that the right answer is the E) The thirst for knowledge and new experiences.
Explanation: Just to elaborate a little on the answer, it can be added that there are several references in the poem, and in this particular passage, to this concept, which turn it into a recurring theme. For instance, the speaker says: "How dull it is to pause [...] To rust unburnish'd" and "[...] this gray spirit yearning in desire to follow knowledge like a sinking star," just to name a few. Like Ulysses before embarking upon his final and challenging voyage, the speaker is also aware that his end is approaching, but rather than waiting for it passively, he decides to face the challenges and the struggles, and, moved by his thirst for knowledge, he keeps pushing onward. The death of a close friend at a very young age inspired Tennyson to write this poem in 1833.
I would say true Tone is a way the author or speaker shows their attitude towards the audience/reader. Right? Well they also have to use diction and punctuation to get proper tone, so yeah I guess it's true.
