They can determine whether something occurred by using real facts that lead to the event happening but it didn’t really happen in history.
Eliminate A, definitely not D. In this sentence, it says, "in a flourishing state in a forest." In some way flourishing is modifying the stick.
And since "stick" is used as a noun, your answer is C.
Hope this helps. If not, feel free to ask questions. :)
The run-on sentence is "She moved to town three months ago, she is pretty shy." because it is combining two correctly-written sentences and conjoining them together.