In the following sentence completion question, choose the correct conjunction to fill in the blank: "Although the school lunch passed the legal standards, __________ or not it is healthy is debatable."

Introduction / Context:
This sentence completion question tests your understanding of the conjunction "whether" and its correct use in clauses that present alternatives, especially with the phrase "whether or not." The sentence talks about school lunch meeting legal standards but questions its actual healthiness. You must choose the correct word that introduces this kind of indirect question or doubt.

Given Data / Assumptions:

• Sentence: "Although the school lunch passed the legal standards, __________ or not it is healthy is debatable."
• The phrase "or not it is healthy" suggests that some kind of "whether or not" structure is intended.
• The options include "weather," "if," "whether," and "either."
• The overall meaning is that we are not sure if the lunch is healthy, even though it meets legal standards.

Concept / Approach:
In English, "whether" is used to introduce indirect questions that include two possibilities, often explicitly expressed as "whether or not." It also appears before clauses that discuss uncertainty or alternatives. "If" can sometimes replace "whether" in certain indirect questions, but it is not usually used with "or not" in subject position like this. "Weather" is a completely different noun referring to climate, and "either" does not function as a conjunction in this context. Therefore, "whether" is the only word that fits grammatically and semantically.

Step-by-Step Solution:
Step 1: Recognise that the structure "__________ or not it is healthy" calls for the phrase "whether or not." Step 2: Understand that "whether" introduces the idea of two alternatives: it may be healthy or it may not be. Step 3: Insert "whether" into the sentence: "Although the school lunch passed the legal standards, whether or not it is healthy is debatable." Step 4: Check that the sentence is now grammatically correct and clearly expresses doubt. Step 5: Rule out other options that do not form a correct expression with "or not."

Verification / Alternative check:
Test each incorrect option: "weather or not it is healthy" is clearly wrong, because "weather" has nothing to do with doubt or alternatives here. "If or not it is healthy is debatable" is ungrammatical; we do not use "if or not" in this subject clause pattern. "Either or not it is healthy" is also incorrect, as "either" normally pairs with "or" to link two alternatives, not with "or not" in this way. Only "whether" produces the natural and standard phrase "whether or not it is healthy is debatable."

Why Other Options Are Wrong:

• weather: A noun referring to climate conditions; completely irrelevant grammatically and semantically.
• if: Sometimes used in indirect questions, but the pattern "if or not it is healthy is debatable" is not standard English, especially with "or not" in this position.
• either: Used to refer to one of two items and pairs with "or," as in "either this or that," not "either or not."

Common Pitfalls:
A common error is confusing "whether" and "weather" because they sound the same. Another frequent mistake is overusing "if" in every kind of clause that expresses doubt. Remember that "whether" is preferred when you explicitly mention alternatives (especially with "or not") and when the clause functions as a subject or object of another verb. In exam sentences, clues like "or not" almost always point to "whether" as the correct choice.

Final Answer:
The correct word is whether, giving the sentence: Although the school lunch passed the legal standards, whether or not it is healthy is debatable.