Improve the bracketed part of the sentence. Human beings are social animals, (who are living in communities), regulated by social norms and laws.

Introduction / Context:
This sentence improvement question tests your understanding of concise, grammatically correct participial phrases. The focus is on removing unnecessary words and choosing the most natural expression in modern academic English while keeping the meaning that human beings live in communities and are regulated by norms and laws.

Given Data / Assumptions:
Original sentence: Human beings are social animals, (who are living in communities), regulated by social norms and laws.
Bracketed part to improve: who are living in communities.
Options offer alternative phrasings for the bracketed part.
You must select the best improvement, or no improvement if the original is best.

Concept / Approach:
In formal English, it is usually better to avoid unnecessary relative pronouns and helping verbs when a simple participial phrase will do. The phrase who are living in communities is wordy, and the continuous aspect are living is not needed for a general truth. The most concise and natural form is living in communities, which functions as a participial phrase directly describing social animals.

Step-by-Step Solution:
Step 1: Consider the intended meaning: Human beings are social animals that live in communities and are regulated by norms and laws. Step 2: The phrase who are living in communities uses who are, which is unnecessary for a general statement about human nature. Step 3: Option A, living in communities, removes who are and correctly uses the present participle living to modify human beings. Step 4: Option B, living amongst a community, is awkward, because amongst a community suggests only one community and an odd prepositional choice. Step 5: Option C, living in midst of communities, is grammatically incomplete; it should be in the midst of, and even then sounds clumsy. Step 6: Option D, no improvement, would keep the wordy original who are living in communities, which is less effective than option A.

Verification / Alternative check:
Insert option A into the sentence: Human beings are social animals, living in communities, regulated by social norms and laws. The sentence now reads smoothly and logically, with living in communities clearly attached to social animals. This confirms that A is the best improvement.

Why Other Options Are Wrong:
Option B restricts the idea to a single community and uses amongst in an unnatural way for this context.
Option C is grammatically flawed because it omits the article the before midst, and it remains a clumsy phrase even if corrected.
Option D ignores the opportunity to make the sentence more concise and idiomatic by removing who are.

Common Pitfalls:
Candidates sometimes hesitate to remove relative pronouns and auxiliary verbs, assuming that longer constructions sound more formal. In reality, examinations reward clear and concise phrasing when it improves readability without changing meaning. Recognising unnecessary who are patterns is an important skill in sentence improvement questions.

Final Answer:
The best improvement of the bracketed part is living in communities (Option A).