What is the main theme reflected in this excerpt from “ulysses” by alfred, lord tennyson?

there gloom the dark broad seas. my mariners,
souls that have toil'd, and wrought, and thought with me--
that ever with a frolic welcome took
the thunder and the sunshine, and opposed
free hearts, free foreheads--you and i are old;
old age hath yet his honour and his toil.
death closes all; but something ere the end,
some work of noble note, may yet be done,
not unbecoming men that strove with gods.

a. the old have free hearts and free minds.
b. the mariners have toiled hard to avoid the dark and broad seas.
c. it is very important to have free time and sunshine in life.
d. the old can regain honor by taking up challenges again.

Why it's time to lay the stereotype of the 'teen brain’ to rest 2. part b: which detail from the text best supports the answer to part a? a “brain deficits don’t make teens do risky things; lack of experience and a drive to explore the world are the real factors.” (paragraph 1) b “according to this theory, the prefrontal cortex, the center of the brain’s cognitive-control system, matures more slowly than the limbic system, which governs desires and appetites including drives for food and sex.” (paragraph 5) c “in experiments that mimic the well-known marshmallow test, in which waiting for a bigger reward is a sign of self-control, adolescents are less impulsive than children and only slightly more so than adults.” (paragraph 12) d “the majority of adolescents do not die in car crashes, become victims of homicide or suicide, experience major depression, become addicted to drugs or contract sexually transmitted infections.” (paragraph 14)