Hi Adashworth,
Answer choice (B) states that Freudianism had adherents who treated Freudianism as a scientific fact. The author does claim that Freudianism had adherents who trusted the theory to explain historical events. Whether they thought of Freudianism as "scientific fact" is less clear.
Even if this statement is supported by the passage, it would still be incorrect. We are not simply told to find one answer choice that is supported by the passage. Rather, we are asked to find the reason that the author thinks that Freudianism is a grand theory.
Remember that your job is not simply to find the statement that is supported. Your job is also not just to find the specidic or the general statement. Rather, you must read the question stem carefully and make sure that you know what it is asking you to look for.
Number 26 asks us to find the reason why the author categorizes Freudianism as a grand theory. Lines 4-7 give us the author's definition of a grand theory and that definition is paraphrased very closely in answer choice (D).
I hope that this helps, but let us know if you have other questions!