In the following sentence, a blank is given which must be filled with an appropriate word or phrasal verb. Select the correct alternative. My sister's marriage passed _____ peacefully.

Introduction / Context:
This question tests your knowledge of English phrasal verbs, which are verb plus particle combinations that often have meanings different from the base verb. The sentence describes how an event, a marriage ceremony, happened. You need to choose the correct particle that forms a natural expression with passed to mean occurred or happened in a certain manner.

Given Data / Assumptions:
Sentence: My sister's marriage passed _____ peacefully.
Options: away, by, off, out.
We are talking about an event, not a person dying or an object moving past.
We assume the intended meaning is that the marriage ceremony took place or happened without problems, in a peaceful manner.

Concept / Approach:
In English, the phrasal verb pass off is commonly used for events and means to happen, especially in a particular way: The event passed off peacefully or The function passed off well. Other combinations like pass away and pass out have different meanings: pass away means to die; pass out means to faint or lose consciousness; pass by means to go past or be ignored. The approach is to recall which phrasal verb collocates naturally with an event and the adverb peacefully.

Step-by-Step Solution:
Step 1: Insert each option mentally into the sentence and check the overall meaning. Step 2: My sister's marriage passed away peacefully would suggest that the marriage died, which is incorrect; pass away is used for death of a person. Step 3: My sister's marriage passed by peacefully implies that the marriage went past like time, which sounds odd when referring to a specific ceremony. Step 4: My sister's marriage passed out peacefully would suggest the marriage fainted, which is clearly wrong; pass out is used for people losing consciousness. Step 5: My sister's marriage passed off peacefully is idiomatic and means that the marriage ceremony took place without trouble or disturbance. Step 6: Therefore, the correct choice is off, forming the phrasal verb passed off.

Verification / Alternative check:
Check other common examples: The protest passed off without any violence, or The examination passed off smoothly. In all such sentences, the structure is passed off plus an adverb describing how the event happened. The same pattern perfectly fits My sister's marriage passed off peacefully, confirming that off is the right particle.

Why Other Options Are Wrong:
Away changes the meaning to death, which is inappropriate and grammatically wrong for a marriage ceremony.
By suggests an event or person simply moving past, not an organised ceremony taking place, so it does not collocate with marriage in this structure.
Out forms pass out, which is used for fainting or distributing items, not for a function or ceremony occurring smoothly.

Common Pitfalls:
Candidates often guess based on partial familiarity with pass away or pass out, forgetting that those phrasal verbs have specific meanings tied to death or fainting. Event-related contexts almost always require passed off when we want to say that something happened in a certain manner. Recognising these fixed patterns is crucial for scoring well in phrasal verb questions.

Final Answer:
The correct completion is off, giving the sentence: My sister's marriage passed off peacefully.