Option 1 -> Places (C) immediately after "begins in the mouth" and ends with (D), disrupting the logical flow of the digestive process description.
Option 2 -> Follows natural progression: introduces digestion starting in mouth (B), continues to stomach/intestines (D), describes the process there (C), and concludes with the result (A).
Option 3 -> Places (A) directly after "begins in the mouth," creating an awkward construction that breaks the sentence flow.
Option 4 -> Begins with (C) "where food is broken down," which is a dependent clause and cannot start the sentence.
Hence, Option 2: (B), (D), (C), (A) -> This arrangement creates a coherent sentence: "Digestion is an intricate process that begins in the mouth and continues in the stomach and intestines where food is broken down mechanically and chemically into simpler molecules that can be absorbed into the bloodstream." It logically traces the digestive journey from start to finish. -> correct