The men represent the dynamic character.
So, B. Dynamic
For a topic sentence, or the beginning sentence that signifies the main idea of the paragraph, you could focus on the fact that there are a variety of things to do at the beach (perhaps the 3rd sentence). To create a hook, or an eye-catching sentence, you can use the childhood memory of learning to swim, but perhaps in more detail. In other words, recreate the scene rather than just saying it was a happy memory (i.e. I'm five years old and am amazed by how weightless I feel in the water). Once you create the hook and topic sentence, you can talk about other activities at the beach as your supporting evidence.
The readers understanding would change without different points of view shown through dialogue because without characters point of view shown through dialogue there is nothing there to form the readers opinion and understanding of the characters feelings and thoughts. In the Hobbit, dialogue is very important for the readers understanding. For example, Bilbo Baggins shares his thoughts, feelings, and ideas throughout his adventures, along with many other characters. Without Bilbo expressing his point of view through dialogue, the reader would have no idea what he is feeling, along with all of the other characters, Dialogue builds a picture in the readers head and without that picture the reader won't have an accurate idea of what the author intended the reader to think.
I hope this helps! :)
Us. It doesn't make sense to say "was more useful to you than to we"