Improve the bracketed part of the sentence by choosing the correct tense and form: His decision (will be fair) to everyone as he is the most disinterested party in this controversy.

Introduction / Context:
This question checks your understanding of verb forms and the correct use of the verb "be" plus an adjective. The sentence predicts something about the fairness of a future decision. We must decide whether the existing phrase "will be fair" is correct or whether it needs any improvement based on standard English grammar.

Given Data / Assumptions:

• The subject is "His decision."
• The bracketed phrase is "will be fair."
• The context is a prediction about the fairness of his future decision.
• We need to confirm the appropriate tense and structure to describe this future state.

Concept / Approach:
When we talk about a future state or quality, we often use "will be" plus an adjective. For example, "The result will be good" or "The journey will be difficult." Here, "fair" is an adjective describing the quality of the decision. The form "will be fair" correctly expresses that in the future, the decision is expected to be fair. None of the alternative verb forms fit the meaning and structure as well as the original phrase.

Step-by-Step Solution:
Step 1: Identify that the sentence is referring to something that has not yet happened, namely his decision. Step 2: Recognise that we normally express future predictions using "will" plus base verb or "will be" plus adjective or noun. Step 3: Notice that "fair" functions as an adjective describing the decision. Step 4: Confirm that "will be fair" is the correct future form here and that no change is needed. Step 5: Read the full sentence: "His decision will be fair to everyone as he is the most disinterested party in this controversy." This sentence is fluent and grammatically sound.

Verification / Alternative check:
We can check similar structures: "Her answer will be honest," "Their proposal will be acceptable," and "The outcome will be fair." In each case, "will be" precedes an adjective that describes a future condition or quality. This pattern matches the bracketed phrase "will be fair." The alternatives either change the meaning or break basic grammatical rules, confirming that the original is correct.

Why Other Options Are Wrong:
Option A: "fairing" is incorrect in this context because "fair" is an adjective here, and "fairing" would not fit as a verb or noun describing the quality of the decision. Option B: "will fair" incorrectly treats "fair" as a main verb. While "fair" can function as a verb in some specialised contexts, in this sentence the intended role is clearly that of an adjective describing the decision. Option C: "had fair" is completely wrong in tense and structure. It uses past perfect "had" with an adjective without a linking verb, making the phrase ungrammatical. Option D: "No improvement" is correct because the phrase "will be fair" accurately and grammatically describes the expected future quality of the decision.

Common Pitfalls:
A common mistake is to treat adjectives as verbs or to confuse the structure "will be" plus adjective with "will" plus main verb. Learners sometimes attempt forms like "will good" or "had honest," which are not correct. Remember that adjectives describing states or qualities generally need a linking verb such as "be," "seem," or "become." In future tense predictions about qualities, "will be" is normally used.

Final Answer:
The phrase "will be fair" is already correct, so the best choice is: No improvement.