A concrete statement can be considered as a 'solid' statement. This means that the sentence must contain hard facts to manifest the credibility of the statement. As much as possible, you give specific examples and provide evidence for this. From the choices, the answer would be D.
As a writer and reader I disagree with this. Perhaps if you are writing for a scientific journal or business report, long blocks of text can seem like you have a lot of info. Generally speaking, especially in fiction and non fiction i think unbroken pages of text will best case scenario bore a reader, worst case scenraio burden and overwhelm them with a lot of info so the feel daunted about continuing.
The preposition in question is "on", and its purpose is to show you where the dog chewed. You can remove the preposition to form the sentence "The brown dog chewed the rawhide bone." You can also rearrange it to find the preposition, "on the rawhide bone, the dog chewed" in what is commonly known as the Yoda technique.
Here's a hint: The rising action is when you its getting interesting
so it would be the first 2 semtences