Which of the following statements is true regarding the ability to consent to marriage?

The statement that a person can be incompetent for other legal purposes but still competent to marry is accurate. In family law, the criteria for mental capacity to consent to marriage is not as stringent as for other legal transactions. This means that individuals may have varying levels of mental competency; they can be deemed incapable in one context (like making a will or entering into a contract) yet still possess the necessary understanding and ability to consent to marriage. This distinction is crucial, as marriage does involve a specific set of criteria regarding the understanding of the partnership and rights involved which might differ from other legal considerations.

In contrast, the other statements do not accurately reflect the legal standards surrounding marriage consent. The notion that everyone has the same legal standard for mental capacity oversimplifies a nuanced issue, as different individuals may be assessed differently based on their understanding and circumstances. The idea that a person must be mentally competent in all legal scenarios is also overly broad; mental capacity can vary depending on the specific legal context. Lastly, while consent to marry is typically restricted to adults, this statement doesn't address the complexities surrounding mental competency as effectively as statement C does.