In the following question, a sentence is divided into numbered parts. Identify the part that contains a grammatical or word choice error. Sentence: “Acquired immunity is the result of an interaction with our new environment and proper digestion of all that we take off.”

Introduction / Context:
This question checks vocabulary and idiomatic usage in a sentence about acquired immunity. The sentence is split into three parts, and the candidate must find which part contains a faulty expression or grammatical error, or decide that the sentence is fully correct. The main focus is the phrase “take off,” which appears at the end of the sentence.

Given Data / Assumptions:

• The sentence reads: “Acquired immunity is the result of an interaction with our new environment and proper digestion of all that we take off.”
• Part (1): “Acquired immunity is the result of an” is grammatically correct.
• Part (2): “interaction with our new environment and” is a natural prepositional phrase.
• Part (3): “proper digestion of all that we take off” contains the phrasal verb “take off.”
• In the context of digestion and immunity, the intended meaning is that we digest everything we consume or take in.

Concept / Approach:
The key concept here is correct idiomatic usage. The phrasal verb “take off” usually means remove, depart, or achieve sudden success. It does not fit with the idea of digestion. In contrast, “take in” is the normal expression for consuming food or drink. Therefore, we must look for the part of the sentence where the idiom does not fit the intended meaning.

Step-by-Step Solution:

Verification / Alternative check:
A quick check is to replace “take off” with “take in” and read the sentence again: “Acquired immunity is the result of an interaction with our new environment and proper digestion of all that we take in.” This version is logically and grammatically correct. It matches normal English usage. Since the only change needed is in part (3), that part must contain the error.

Why Other Options Are Wrong:

• Part (1): There is no error in tense, article usage, or word order.
• Part (2): The preposition “with” and the noun phrase “our new environment” are both appropriate.
• “No error”: This option cannot be right because the idiom “take off” clearly does not express the intended meaning of consuming food for digestion.

Common Pitfalls:
Examinees sometimes focus only on grammar and ignore word choice, so they may overlook the incorrect phrasal verb. Others may be unsure about the exact meaning of “take off” and therefore fail to recognise that it is inappropriate here. To avoid such mistakes, it is important to consider both grammatical correctness and logical meaning when evaluating sentence parts for errors.

Final Answer:
Part (3) is the correct answer because the expression “take off” should be “take in” to match the context of digestion and acquired immunity.