In the following sentence improvement question on modal verbs, choose the correct option to replace the bracketed verb so that the sentence is grammatically correct and natural: "I am the only man in the world who (can) paint a picture so true to life," he said.

Introduction / Context:
This question tests your understanding of relative clauses and the correct use of modal verbs in English. The sentence is a self confident statement: "I am the only man in the world who can paint a picture so true to life," he said. We need to decide whether the modal "can" is appropriate, or whether an alternative modal verb such as "will", "could" or "may" would better convey the intended meaning.

Given Data / Assumptions:

• Speaker is talking about his current, general ability.
• Sentence structure: main clause "I am the only man in the world" plus relative clause "who can paint a picture so true to life".
• The verb in the relative clause must agree with the present claim of capability.
• The context suggests strong assurance, not just possibility or permission.

Concept / Approach:
The modal "can" is commonly used to express ability. In relative clauses beginning with "who", when we describe what someone is capable of doing at present, we use "can" to show that the ability exists now. Other modals like "could" may express past ability or a weaker, hypothetical sense, while "may" expresses permission or possibility. "Will" usually refers to future actions or willingness, which does not fit with the idea of a general present talent.

Step-by-Step Solution:
Step 1: Identify the time frame: "I am" is present tense, so the ability should also be expressed in the present. Step 2: Recognise that the speaker is claiming a unique ability in the world. Step 3: Match this with the modal that expresses present ability, which is "can". Step 4: Check each alternative: "will" (future), "could" (past or tentative ability), "may" (permission or possibility) do not match the confident present claim. Step 5: Conclude that the original wording with "can" is already correct, so "no improvement" is the right choice.

Verification / Alternative check:
If we substitute each option into the sentence, we get versions like "who will paint", "who could paint", or "who may paint". None of these expresses a strong present ability in the same way as "who can paint". They either shift the time frame or weaken the certainty. Therefore the original modal "can" is the best and most natural choice in standard English, confirming that no improvement is needed.

Why Other Options Are Wrong:
Option a: "will" suggests future action or determination, not a general talent that exists now. Option b: "could" often refers to past ability or a polite hypothetical statement, which does not suit the proud present claim. Option c: "may" usually expresses permission or possibility and sounds unusual when describing a personal skill.

Common Pitfalls:
Students sometimes change modals simply because they see one in brackets, assuming it must be wrong. Another mistake is to focus only on one part of the sentence without checking tense consistency between the main clause and the relative clause. Always consider whether the speaker is talking about present, past, future, or hypothetical situations before you decide on the correct modal verb.

Final Answer:
The sentence is already correct, so the right choice is no improvement.