The risk owner is listed as the department responsible for decision making would pose the greatest concern for a risk practitioner who is reviewing accountability assignments for data risk in the risk register, as it indicates a lack of clarity and specificity on who is accountable for the risk and its response. The risk owner should be an individual, not a department, who has the authority and responsibility to manage the risk and its associated controls. The other options are not the greatest concern, as they do not necessarily imply a lack of accountability, but rather a possible difference in roles and responsibilities between the risk owner and the control owner, the business unit and the IT department, or the staff member and the department manager. References = CRISC Review Manual, 7th Edition, page 101.