In this vocabulary question, choose the option which best expresses the meaning of the English word "Espionage".

Introduction / Context:
This vocabulary question is about the word "espionage", which frequently appears in news reports, history books, and discussions of international relations. Understanding its meaning is important for reading comprehension in topics involving security, intelligence agencies, and war. You are asked to select the option that is closest in meaning to "espionage".

Given Data / Assumptions:

• Target word: "Espionage".
• Option A: "hypnotism"
• Option B: "spying"
• Option C: "perception"
• Option D: "detente"
• We assume you are familiar with basic international and security terminology.

Concept / Approach:
"Espionage" is the practice of secretly collecting information, especially about a foreign government or a competing organisation, usually for political or military purposes. In simpler terms, it means "spying". It often involves secret agents, covert operations, and intelligence gathering. The other options refer to unrelated concepts: "hypnotism" is a psychological technique, "perception" relates to awareness or understanding, and "detente" refers to a relaxation of political tension between countries. Thus, the direct synonym here is "spying".

Step-by-Step Solution:
Step 1: Recall the basic definition of "espionage": the secret collection of information, often by spies.Step 2: Compare it with "spying", which means secretly observing or gathering information, especially in a political or military context.Step 3: Note that "hypnotism" concerns putting someone into a trance like state, not secret information gathering.Step 4: Recognise that "perception" is about how we interpret and understand stimuli, not about covert operations.Step 5: Understand that "detente" is a diplomatic term meaning the easing of strained relations, especially between countries, and is effectively the opposite context of espionage related tension.

Verification / Alternative check:
Consider a typical sentence: "He was arrested for espionage against the state." If we substitute "spying", we get: "He was arrested for spying against the state." This keeps the meaning intact. If we try the other words, the sentence becomes meaningless or incorrect: "arrested for hypnotism against the state" or "arrested for perception" clearly do not work. "Arrested for detente" is also nonsense. Therefore, "spying" is the only valid synonym in this list.

Why Other Options Are Wrong:

• Option A "hypnotism" refers to a technique used in psychology or stage performances where a person is put into a state of increased suggestibility.
• Option C "perception" describes how we see, hear, or become aware of something; it does not involve secret gathering of information.
• Option D "detente" refers to improved relations or the easing of hostility between countries, often the opposite atmosphere where espionage thrives.

Common Pitfalls:
Students may be confused by "detente" because it is also a political term and often appears in discussions of international relations. However, its meaning is nearly opposite that of "espionage" because detente lowers tensions while espionage can increase suspicion and conflict. Keeping political vocabulary clear in your mind helps avoid such confusion in exams that mix history, politics, and English usage.

Final Answer:
The option that best expresses the meaning of "espionage" is "spying".