In the following English vocabulary question, you are given a short descriptive phrase. Choose, from the four alternatives, the one word that best substitutes the phrase "200th anniversary".

Introduction / Context:
This is a one word substitution question about anniversaries and time intervals. The phrase given is 200th anniversary. You have to identify which word among the options correctly names the celebration of two hundred years. This type of question commonly appears in general English sections to test knowledge of numerical prefixes and time related vocabulary.

Given Data / Assumptions:

• The phrase given is 200th anniversary.
• Option A: Quadriennial.
• Option B: Bicentennial.
• Option C: Quinquennial.
• Option D: Bimillennial.
• We assume each word uses Latin based numerical prefixes like bi, quinque and so on, combined with roots that relate to years or centuries.

Concept / Approach:
The root cent in English often refers to a hundred, as in century which means one hundred years. The prefix bi means two. Thus, bicentennial refers to the 200th anniversary, that is, the completion of two hundred years since an event. Quadriennial combines quadri (four) and ennial (years) and refers to something happening every four years. Quinquennial refers to a five year period. Bimillennial would relate to two thousand years rather than two hundred years.

Step-by-Step Solution:
Step 1: Focus on the number in the phrase: 200th tells us that the event marks two hundred years.Step 2: Identify the relevant number roots in the options. Bi suggests two, cent suggests hundred, mill suggests thousand, quadri suggests four, and quinque suggests five.Step 3: Combine bi plus cent to get two hundred, and note that bicentennial is widely used for 200 year celebrations.Step 4: Recognise that quadriennial refers to something occurring every four years, such as a quadriennial sports event, and is not about a 200 year anniversary.Step 5: Note that quinquennial refers to a period of five years, and bimillennial relates to two thousand years. Neither matches the idea of a 200th anniversary, so bicentennial is the only correct choice.

Verification / Alternative check:
Think of how these words appear in real contexts. Historic events like the adoption of a constitution or the founding of a city often have bicentennial celebrations two hundred years later. You may have read about bicentennial parades or bicentennial stamps issued in honour of 200 years. In contrast, a quinquennial plan is a five year plan, and quadriennial elections happen every four years. These uses confirm that bicentennial belongs with 200th anniversary, not the other options.

Why Other Options Are Wrong:
Quadriennial is based on quadri meaning four and annus meaning year, and it describes an event that recurs every four years rather than an exact 200 year celebration. Quinquennial is tied to the number five and is used for five year periods or events. Bimillennial suggests two thousand years, such as a bimillennial celebration two millennia after an event. None of these alternatives expresses the idea of exactly two hundred years passing since a particular date.

Common Pitfalls:
Students sometimes confuse centennial and bicentennial or misinterpret the bi prefix as referring to two years instead of two units of a hundred years. It is helpful to remember a small set of related words together: centennial for 100 years, bicentennial for 200 years, tricentennial for 300 years, and so on. Linking these words with familiar events like national founding anniversaries can make them much easier to remember in exam conditions.

Final Answer:
The correct one word substitute for 200th anniversary is Bicentennial, so option B is correct.