In English vocabulary, which of the following words is the best one-word substitute for the phrase "belonging to the middle class"?

Introduction / Context:
One-word substitutions are a common component of English language questions in competitive exams. They test the candidate’s vocabulary depth and understanding of precise meanings. Here, the phrase "belonging to the middle class" must be replaced by the most suitable single word from the options. Knowing the social and economic connotations of these terms is essential to choosing correctly.

Given Data / Assumptions:

• The phrase to be substituted is "belonging to the middle class".
• The options include words with very different meanings: chamois, turquoise, bourgeois, envious and opulent.
• Only one of these words directly refers to social class, specifically the middle class.
• The question assumes basic familiarity with English words of French origin and their common usage.

Concept / Approach:
The word "bourgeois" comes from French and in modern English typically refers to someone belonging to or characteristic of the middle class, often with implications of conventional attitudes and concern for material possessions. This fits the given phrase very closely. The other words largely refer to colours, feelings or wealth, not to social class itself. Therefore, the correct approach is to identify which word explicitly connects to the middle class concept.

Step-by-Step Solution:
Step 1: Understand the phrase "belonging to the middle class" as describing social and economic status.Step 2: Examine each option: "chamois" is a type of soft leather or an animal; "turquoise" is a blue green colour or gemstone; "bourgeois" relates to middle class people; "envious" refers to feeling jealousy; "opulent" means very rich or luxurious.Step 3: Identify that only "bourgeois" clearly describes the social class mentioned in the phrase.Step 4: Confirm that this word is commonly used in phrases like "bourgeois values" or "bourgeois lifestyle", which directly connect to middle class identity.Step 5: Select "Bourgeois" as the correct answer.

Verification / Alternative check:
A simple verification is to try substituting each option into a sample sentence, such as "He holds many ___ attitudes typical of the middle class." "He holds many bourgeois attitudes" is natural and meaningful. In contrast, "chamois attitudes", "turquoise attitudes", "envious attitudes" or "opulent attitudes" either sound absurd or change the meaning. This substitution test confirms that "bourgeois" is the appropriate one-word substitute.

Why Other Options Are Wrong:
"Chamois" refers to leather or an animal and has no link to social class. "Turquoise" is primarily a colour or stone, again unrelated to class. "Envious" describes a state of jealousy, which is an emotion, not a class identity. "Opulent" means rich or luxurious and could describe a lifestyle but does not specifically mean middle class; in fact, it usually implies a very wealthy or upper class status. Hence these options do not match the exact phrase given.

Common Pitfalls:
Some candidates may be tempted by "opulent" because they associate the middle class with wealth, but this misreads the phrase; "opulent" refers to richness, not to the middle class category. Others might pick a word simply because it looks sophisticated or foreign. It is important to focus on the precise dictionary meaning rather than on how impressive a word appears. Learning common one-word substitutions, especially those drawn from French like "bourgeois", can significantly boost exam performance.

Final Answer:
The correct answer is Bourgeois.