Which of the following actions can JASA guardians undertake?

JASA guardians have the responsibility to manage the financial and personal affairs of individuals who are unable to do so themselves, typically due to incapacity. Marshaling assets refers to the process of identifying, collecting, and securing the assets of the individual under guardianship. This is a fundamental duty of a guardian, as it is essential to ensure that the individual's resources are safeguarded and appropriately managed for their needs.

While a guardian can handle a variety of tasks related to the well-being of the person they represent, such as making healthcare decisions or managing finances, the role does not typically involve investing in real estate, running a business, or managing family disputes. Each of those actions involves additional complexities and potential conflicts of interest that exceed the standard scope of a guardian's responsibilities. Thus, the primary function of a JASA guardian, which aligns with the correct answer, is to marshal assets effectively, ensuring that the wards they serve are cared for in a responsible and ethical manner.