Directions: Rearrange the given sentences in a logical sequence to form a coherent paragraph, then answer the question below.

(A) He found that a high percentage of patients experienced functional loss before age 50.
(B) Recently, medical researchers identified a cellular protein linked to aggressive forms of Parkinson's.
(C) Parkinson’s is a progressive neurological disorder that gradually disrupts movement and motor control.
(D) Prompted by this discovery, Dr. Vance analyzed patient records from 40 major hospitals.
(E) These findings underscore the critical need for early diagnostic tools and targeted interventions.
(F) This ongoing physical decline is compounded by the reality that current medications merely address symptoms.

Which of the given sentences should be the FOURTH sentence after the paragraph is properly arranged?

To determine the correct logical sequence of the given sentences, let us analyze the contextual links and pronoun references between them step-by-step:

1. Sentence (C) serves as the ideal opening sentence because it introduces the main topic, defining Parkinson's disease as a progressive neurological disorder that disrupts movement and motor control.
2. Sentence (F) logically follows sentence (C). The phrase "This ongoing physical decline" directly refers back to the progressive disruption of movement mentioned in (C).
3. Sentence (B) introduces a recent scientific breakthrough, stating that researchers identified a cellular protein linked to aggressive forms of Parkinson's.
4. Sentence (D) connects directly to (B) using the phrase "Prompted by this discovery," where "this discovery" refers to the identification of the cellular protein in sentence (B). This sentence also introduces Dr. Vance.
5. Sentence (A) follows sentence (D) by detailing what Dr. Vance found during his analysis ("He found that a high percentage of patients experienced functional loss before age 50").
6. Sentence (E) concludes the paragraph by summarizing the overall significance of Dr. Vance's results ("These findings underscore the critical need for early diagnostic tools and targeted interventions").

Combining these sentences gives the coherent paragraph order: C – F – B – D – A – E.

Tracing the positions in the proper arrangement:
• 1st sentence: (C)
• 2nd sentence: (F)
• 3rd sentence: (B)
• 4th sentence: (D)
• 5th sentence: (A)
• 6th sentence: (E)

Therefore, the fourth sentence in the properly arranged paragraph is D.