In this passage about the changing experiences of life, choose the option that best completes the sentence "If a man is happy today, he may be ______ unhappy the very next day."

Introduction / Context:
This English grammar multiple choice question is based on a cloze passage about the ups and downs of life. The specific sentence asks us to complete the phrase "he may be ______ unhappy the very next day". The task is to select the adverb that fits best in normal English usage and expresses the correct degree of unhappiness within the context of the passage about changing experiences in life.

Given Data / Assumptions:

The wider passage states that life is full of many types of experiences, both pleasant and painful.
The key sentence is "If a man is happy today, he may be ______ unhappy the very next day."
We must choose the most appropriate word from the given options to complete this sentence in standard English.
We assume normal modern usage of British or Indian English grammar and vocabulary for competitive exams.

Concept / Approach:
This item tests knowledge of adverbs of degree and collocations in English. The word placed before the adjective "unhappy" should modify the intensity of the unhappiness in a natural and idiomatic way. Common collocations like "quite unhappy", "very unhappy", and "deeply unhappy" are natural. Words like "most", "quietly", or "major" do not usually precede "unhappy" in this structure. Therefore the approach is to check meaning, grammar, and common usage patterns in context.

Step-by-Step Solution:
Step 1: Read the complete sentence: "If a man is happy today, he may be ______ unhappy the very next day." Step 2: Notice that the blank comes before the adjective "unhappy", so we require an adverb or degree word which modifies "unhappy". Step 3: Test each option in the sentence: "most unhappy", "quietly unhappy", "quite unhappy", "major unhappy", and "very unhappy". Step 4: "Quite unhappy" is a very common and natural English expression that means "rather unhappy" or "considerably unhappy", and it matches the contrast between being happy one day and significantly unhappy the next. Step 5: Confirm that "quite" functions as an adverb of degree and fits both grammatically and contextually better than the other options in this cloze passage.

Verification / Alternative check:
To verify, read the surrounding idea from the passage. The text explains that life contains both happy and sad experiences and that a person can move quickly from one emotional state to another. When we insert "quite" in the sentence, we get "If a man is happy today, he may be quite unhappy the very next day." This sentence is smooth, idiomatic, and clearly shows the contrast. Other choices either sound awkward or change the meaning. Therefore, "quite" is the most suitable filler.

Why Other Options Are Wrong:

"most": The phrase "most unhappy" is grammatically possible but usually requires a definite context like "the most unhappy person". Here we are not making a comparison; we only want a moderate degree, so it does not fit well.
"quietly": This describes manner, not degree. "Quietly unhappy" means unhappy in a silent way, which is not the focus of the passage. The passage focuses on degree and change, not on manner.
"major": "Major unhappy" is not a natural English collocation. "Major" usually modifies nouns like "major problem", not adjectives like "unhappy" in this way.
"very": Although "very unhappy" is possible, competitive exam cloze passages are usually created around a particular intended word. The standard collocation and expected exam key here is "quite unhappy".

Common Pitfalls:
Many learners quickly choose "very" because it is a familiar intensifier. Others may choose "most" under the impression that it gives a strong effect. However, cloze test questions depend on the most idiomatic and intended collocation. Ignoring collocation and only thinking about literal meaning often leads to mistakes. Another pitfall is to overlook the nuance between "quite unhappy" which suggests a considerable but not extreme degree of sadness, and "most unhappy" which sounds like an absolute superlative in many contexts.

Final Answer:
The correct word to complete the sentence is "quite".