Choose the most appropriate word to complete the sentence: Mount Everest has earned the _____ distinction of being the world's highest garbage dump.

Introduction / Context:
This question checks your understanding of collocations and nuanced vocabulary in English. When we speak of a distinction, we often pair it with adjectives like high, special, honorary, or dubious. The sentence here is ironic, because being the world s highest garbage dump is not a positive distinction.

Given Data / Assumptions:
- Sentence: Mount Everest has earned the _____ distinction of being the world s highest garbage dump. - Options: marked, disgusting, dubious, dismal. - The expression is about a negative or shameful kind of distinction. - Standard collocations in journalism and formal writing are assumed.

Concept / Approach:
The phrase dubious distinction is a common collocation used to describe an honour or distinction that is actually negative, shameful, or questionable. It indicates that although something is noteworthy, it is not something to be proud of. Therefore, we must select the adjective that naturally forms this phrase. The other adjectives do not usually collocate with distinction in this way.

Step-by-Step Solution:
Step 1: Recognise that being a garbage dump is not a positive achievement. Step 2: Recall the fixed phrase dubious distinction, used for negative records or achievements. Step 3: Test option C, dubious, in the sentence: has earned the dubious distinction of being the world s highest garbage dump. Step 4: Check option A, marked. Marked distinction is possible, but it emphasises clear difference rather than negative irony, and it is uncommon in this exact phrase. Step 5: Check option B, disgusting. Disgusting describes something revolting but does not collocate well with distinction. Step 6: Check option D, dismal, which describes something very bad or gloomy, again not fitting the fixed expression. Step 7: Therefore, dubious is the most suitable and idiomatic choice.

Verification / Alternative check:
Look at other examples: This city has the dubious distinction of having the worst traffic in the country. That company holds the dubious distinction of the highest number of complaints. In each case, dubious distinction highlights a negative achievement. Replacing the blank with dubious in the Mount Everest sentence creates exactly this kind of ironic negative honour.

Why Other Options Are Wrong:
Marked in option A suggests clear or noticeable, but marked distinction is not a standard phrase used for negative records. Disgusting in option B is too direct and does not grammatically pair with distinction in standard usage. Dismal in option D conveys misery or very poor quality but again does not fit well before distinction.

Common Pitfalls:
Students sometimes choose adjectives based only on negative meaning without checking fixed expressions. English has many collocations where one particular adjective is strongly preferred, such as heavy rain, strong tea, and dubious distinction. Ignoring these patterns can lead to unnatural sentences. It is useful to note such fixed combinations when reading newspapers and magazines.

Final Answer:
The correct word is dubious, giving the phrase the dubious distinction.