In each of the following questions, four words are highlighted in bold. These bold words may or may not be placed correctly in the sentence. The sentence is followed by answer choices that show the correct pair(s) of words that need to be exchanged with one another so that the sentence becomes both grammatically accurate and contextually meaningful. Identify the right combination of word swaps. If the sentence requires no changes, choose option (E).

Dumping of industrial channel (A) leads present (B) to aquatic animals harm (C) in the deeper waste (D) of the river.

The correct answer is Only (A) -(D) and (B) -(C).

Step 1: Analyze the original sentence
The given sentence is: "Dumping of industrial channel (A) leads present (B) to aquatic animals harm (C) in the deeper waste (D) of the river."
In its current state, phrases like "industrial channel", "leads present", and "deeper waste" are contextually inappropriate and grammatically incorrect.

Step 2: Analyze the swap between (A) and (D)
- Exchanging word (A) channel with word (D) waste forms the term "industrial waste", which logically fits the context of "dumping".
- Consequently, placing channel at position (D) creates the meaningful phrase "deeper channel of the river".

Step 3: Analyze the swap between (B) and (C)
- Exchanging word (B) present with word (C) harm places "harm" after "leads" ("leads harm to...") and "present" after "aquatic animals" ("aquatic animals present...").
- This accurately describes that dumping industrial waste leads to harm for the aquatic life existing/present in that part of the river.

Step 4: Verify the fully corrected sentence
"Dumping of industrial waste leads harm to aquatic animals present in the deeper channel of the river."
Since both swaps are required to make the sentence grammatically accurate and contextually meaningful, the correct combination of word swaps is (A) -(D) and (B) -(C).