In the context of a passage on cultural heritage, complete the sentence: The ______ of our cultural heritage has come under the influence of Western culture.

Introduction / Context:
This question checks your understanding of figurative vocabulary. The sentence talks about cultural heritage being attacked or weakened by Western culture, and uses a metaphor from warfare or defence. We must pick a word that fits this image and makes sense in context.

Given Data / Assumptions:
• The sentence refers to our cultural heritage as something that can be defended or attacked.
• The blank is followed by of our cultural heritage.
• The overall idea is that Western culture is threatening or influencing something central and strong in that heritage.
• The correct word should logically fit this metaphor of defence and strength.

Concept / Approach:
The key idea is to recognise that citadel is a metaphor for a strong fortress or central stronghold. In many texts, the citadel of tradition or the citadel of faith refers to the core, most strongly defended part of a belief system. That is exactly the sense needed here for cultural heritage.

Step-by-Step Solution:
Step 1: Note that the sentence talks about our cultural heritage being under pressure from Western culture. Step 2: Recognise that the writer is using figurative language, comparing cultural heritage to a defended place. Step 3: Recall that citadel means a fortress or a stronghold, usually at the centre of a city. Step 4: Test the phrase the citadel of our cultural heritage and see that it sounds natural and meaningful. Step 5: Confirm that none of the other options express the same idea of a strong central fortress.

Verification / Alternative check:
Try replacing the blank with each option: the source of our cultural heritage, the minaret of our cultural heritage, the altar of our cultural heritage, and the citadel of our cultural heritage. Only citadel retains the idea of something that can come under attack and that symbolises strong defence and core strength.

Why Other Options Are Wrong:
Source: This means origin, not stronghold. It does not fit a metaphor of defence or attack.
Minaret: This is a tall tower in a mosque and is specific to a particular religious architecture, making it contextually unsuitable and misleading.
Altar: This refers to a place of worship or sacrifice, not to a defensive structure, so it does not match the idea of something coming under attack in a military sense.

Common Pitfalls:
A common error is to choose source because students see heritage and immediately think of origins. Another mistake is to ignore the figurative, military tone of the sentence and pick a word only on the basis of its association with religion or culture.

Final Answer:
The correct answer is citadel, because it metaphorically represents the strong central fortress of our cultural heritage that has come under the influence or attack of Western culture.