Your answer would be the following one: Kant uses a cause and effect organizational strategy in this excerpt. Cause and effect is a common organizational pattern used in academic writing. If you choose to apply this pattern, you should explain the reasons why something happened or the effects of something. What is more, cause and effect text structure is generally used in expository and persuasive pieces of work. In this case, the cause of the enlightenment of the public is freedom.
Which Dubois work is this? The Soul of Black Folk or another?
The form of punctuation that is being referred to in this question is
most likely the exclamation mark. Exclamation marks should never be used
in formal or professional writing, because they will immediately make
the individual writing seem unprofessional, and even rude.
A speech topic that would be appropriate for a group of retirees would be, to me, to explain that once retired from one's main employer life and one's aspirations and drive do not end there. For example, it is still possible to earn money but less strenuously and rigid than punching a clock by, for example doing freelance work on the internet. Also, now that there is more time, one can pursue his/her real interests of say, writing a book, becoming an artist or supporting progressive politics, for example.