Under the Mental Health Capacity Act 2005, what presumption is made about someone who lacks capacity to make some decisions?

The correct answer reflects the principle that under the Mental Health Capacity Act 2005, it is understood that an individual's capacity can vary depending on the specific decision at hand. The act emphasizes a decision-specific assessment of capacity, meaning that a person may have the ability to make some decisions while lacking capacity in others. This aligns with the Act’s core tenet of empowering individuals, presuming that everyone has the right to make their own decisions unless proven otherwise in relation to a particular matter. This approach ensures that individuals are given the opportunity to make judgments about various aspects of their lives, depending on their understanding and the situation they are facing at the time.

In contrast, the other options suggest a blanket presumption of incapacity across the board or imply a static or universal state of mental incapacity, which does not align with the Act's intention of assessing capacity on a case-by-case basis.