Which of the following is an example of expressed consent?

Expressed consent occurs when a patient explicitly agrees to receive medical treatment or care. This can be communicated verbally or in writing, indicating that the patient is fully aware of what treatment will involve and consents to it. In the context of the question, a patient verbally agreeing to treatment represents a clear, affirmative action demonstrating that they understand and accept the proposed medical intervention.

The other scenarios provided do not constitute expressed consent. Treating a patient without any consent goes against ethical and legal standards in healthcare, as it does not acknowledge the patient's autonomy. A patient showing no reaction does not imply consent; rather, it may indicate a lack of understanding or awareness, which is insufficient for valid consent. Finally, a patient declining treatment after being informed about the risks indicates that they are exercising their right to make decisions about their healthcare, but it does not reflect an agreement to treatment.