**Core Concept**
The question tests the understanding of the concept of informed consent in psychiatric patients. Informed consent is a crucial aspect of medical ethics, ensuring that patients are aware of the potential risks and benefits of a medical procedure. In psychiatric patients, obtaining consent can be challenging due to their mental health condition, which may impair their ability to make informed decisions.

**Why the Correct Answer is Right**
The correct answer is that consent for examination in a psychiatric patient is given by a legally authorized representative, such as a family member or guardian. This is because psychiatric patients may lack the capacity to provide informed consent due to their mental health condition. The Mental Health Act allows for a legally authorized representative to provide consent on behalf of the patient. This ensures that the patient's rights are protected while also allowing for necessary medical treatment.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the patient themselves cannot provide informed consent if they have a psychiatric condition that impairs their ability to make decisions.

**Option B:** This option is incorrect because a general practitioner or any other medical professional cannot provide consent on behalf of the patient without a legal authorization.

**Option C:** This option is incorrect because the patient's wishes, if they have expressed them, are not sufficient to provide consent if they lack the capacity to make informed decisions.

**Clinical Pearl / High-Yield Fact**
It is essential to note that the Mental Health Act and local laws govern the process of obtaining consent for psychiatric patients. Healthcare providers must be aware of these laws and regulations to ensure that they obtain consent in a manner that respects the patient's rights and dignity.

**Correct Answer: D. A legally authorized representative.**