Let's analyze the sentence and the options carefully:
Sentence:
"Maria had successfully navigated complex literary tomes that would have intimidated some scholars, yet she had difficulty following the incoherent plot of this particular book, as, in her opinion, it was far too $\qquad$ to be readable."
- The key word is "incoherent" describing the plot.
- Maria finds the plot too $\qquad$ to be readable, implying it lacks clarity or logical connection.
- We are asked for two answers.

Meanings of the options:
- A. monotonous - dull and repetitious; lacking variety (not necessarily incoherent)
- B. fallacious - based on a mistaken belief; misleading (can mean logically wrong, but less about incoherence)
- C. chaotic - in a state of complete confusion and disorder (fits "incoherent")
- D. disjointed - lacking a coherent sequence or connection; fragmented (fits "incoherent")
- E. erroneous - incorrect or mistaken (more about being wrong, less about coherence)
- F. complicated - complex or difficult to understand (close, but not necessarily incoherent or unreadable)

Best fits for "incoherent" and "too $\qquad$ to be readable":
- C. chaotic - emphasizes disorder and confusion, matching "incoherent."
- D. disjointed - emphasizes lack of logical connection or flow, matching "incoherent."

Less fitting options:
- Monotonous, fallacious, erroneous deal more with being dull or wrong rather than incoherent.
- Complicated means complex but not necessarily incoherent or unreadable.

Final answers:
C. chaotic
D. disjointed