Final answer:
A deed that is voidable due to the grantor's mental incompetence can be set aside later by legal proceedings.
Step-by-step explanation:
A deed which is voidable because the grantor is, in fact, mentally incompetent may be set aside later by legal proceedings.
When a grantor is mentally incompetent, they lack the legal capacity to understand the consequences of their actions and enter into a legally binding contract. As a result, any deed executed by them can be challenged in court, and if it is determined that the grantor was indeed mentally incompetent at the time of execution, the deed can be set aside or voided.
This is different from a deed that is void from the beginning, as a voidable deed means that it remains valid until it is challenged and set aside.