In this English vocabulary question, select the single word that best substitutes the phrase "a group of people leading the way in new developments or ideas".

Introduction / Context:
This question tests your knowledge of one word substitutes, a very important area in English vocabulary for competitive exams. You are asked to choose the word that correctly represents "a group of people leading the way in new developments or ideas". Such a group is usually at the front of progress, innovation, and change in fields like technology, art, politics, or social movements.

Given Data / Assumptions:

• The phrase given describes people who are at the front of new developments and ideas.
• The options provided are "Vanguard", "Sycophant", "Stooge", "Zealot", and "Mediocrity".
• You must match the phrase with the most appropriate English word.

Concept / Approach:
In vocabulary questions like this, you should carefully analyse the key idea in the phrase. The phrase clearly points to leadership in innovation and progress. The word "vanguard" is commonly used for the forefront of an action or movement. Other options have negative or unrelated meanings, so they can be eliminated by understanding their definitions. Good vocabulary preparation involves not only learning meanings, but also typical usage in sentences and contexts.

Step-by-Step Solution:
Step 1: Identify the central idea in the phrase: being at the front of new developments. Step 2: Recall the meaning of "vanguard". It refers to the foremost part of an army or movement, especially those leading in new ideas or trends. Step 3: Check "sycophant". This means a person who flatters someone in power for personal gain. Step 4: Check "stooge". This is a person who is used by someone else as a tool, often in a dishonest or comic manner. Step 5: Check "zealot". This means a person who is fanatically devoted to a cause, not necessarily someone leading new developments. Step 6: "Mediocrity" refers to average quality, not leadership in innovation. Step 7: Only "vanguard" fits the idea of a leading group in new developments.

Verification / Alternative check:
You can verify by remembering common phrases like "the vanguard of the movement" or "the vanguard of technological progress". In both examples, the vanguard clearly refers to those at the forefront. No other option is used in such expressions. This confirms that "vanguard" is the correct answer for the phrase given in the question.

Why Other Options Are Wrong:
"Sycophant" is wrong because it is about flattering behaviour, not leadership. "Stooge" is wrong because it implies being controlled or used by someone else. "Zealot" stresses extreme enthusiasm or fanaticism, not necessarily being at the front of new ideas. "Mediocrity" is also wrong because it suggests average or inferior quality, the opposite of the cutting edge implied by the phrase.

Common Pitfalls:
A common mistake is selecting a word just because it sounds sophisticated or uncommon without knowing its meaning. Some students may also confuse "zealot" with leadership, thinking strong passion equals being a leader, but the word does not guarantee innovation or progress. Always base your choice on precise meanings and common collocations you have seen in reading practice.

Final Answer:
The correct one word substitute is Vanguard.