Sentence Improvement

Step 1: Understanding the sentence.
The sentence suggests that the doctor took an action to send the patient to a specialist. Therefore, the verb should indicate that action of sending or advising.

Step 2: Analyzing the options.
- (A) referred: This is the correct verb choice, as "referred" means the doctor directed the patient to a specialist.
- (B) deferred: This means to delay or postpone, which does not fit the context.
- (C) recommended: While "recommended" could make sense in some contexts, it doesn't strongly convey the action of sending someone to another specialist.
- (D) no change is required: There is a need to change the verb to match the context.

Step 3: Conclusion.
The correct answer is (A) referred, as it most accurately matches the intended action in the sentence.