Out of the following options, select the best one-word substitute for the phrase "conformity to facts".

Introduction / Context:
This question tests your knowledge of one-word substitutes, which are single words that can replace longer descriptive phrases. The phrase conformity to facts refers to the quality of being true and accurate. You must pick the single word that best captures this idea of factual correctness and truthfulness.

Given Data / Assumptions:

- Phrase: conformity to facts. - Options: Veracity, Deceit, Hypothesis, Theory. - The phrase is about truth and correspondence with reality. - Only one option should denote truthfulness or accuracy.

Concept / Approach:
Veracity is a noun that means truthfulness and accuracy. If a statement has veracity, it matches the facts. The phrase conformity to facts is essentially another way of saying adherence to truth, so veracity is the natural one-word substitute. The other options, deceit, hypothesis, and theory, refer to dishonesty or types of explanation, none of which directly express factual correctness.

Step-by-Step Solution:
Step 1: Paraphrase conformity to facts as agreement with reality and truth. Step 2: Consider Veracity, which dictionaries define as devotion to the truth or conformity with fact. Step 3: Notice that this meaning aligns perfectly with the given phrase. Step 4: Look at Deceit, which means dishonest behaviour or trickery, the exact opposite of being truthful. Step 5: Examine Hypothesis, which is a proposed explanation that still needs to be tested and may or may not conform to facts. Step 6: Check Theory, which is a system of ideas or explanation that may be supported by evidence but is not itself a direct synonym for truthfulness. Veracity remains the only direct match.

Verification / Alternative check:
Use the options in sample sentences. The veracity of his statement was never doubted clearly means the truthfulness of his statement. Conformity to facts fits well as a synonym here. If we try The deceit of his statement or The hypothesis of his statement, the meaning changes completely. Similarly, the theory of his statement is not idiomatic. Thus, veracity is the only option that keeps the original idea intact.

Why Other Options Are Wrong:
Deceit implies lying or cheating and directly opposes the idea of conforming to facts. Hypothesis refers to a tentative explanation that still needs proof and is not guaranteed to match reality. Theory denotes a well developed explanation, often supported by evidence, but does not mean simple truth or factual accuracy in itself. None of these words capture the straightforward idea of being factual and true.

Common Pitfalls:
One common error is to choose hypothesis or theory simply because they are academic sounding and relate to knowledge. However, the phrase conformity to facts is about truth, not about models or ideas. To avoid such mistakes, always restate the phrase in your own simple words and then match that restatement to the option that fits best. Here, truthfulness or factuality clearly leads you to veracity.

Final Answer:
Veracity is the correct one-word substitute for conformity to facts.