1. Project Management Institute. (2017). The Standard for Program Management (4th ed.). Section 5.5
Implement Program Risk Responses
p. 79. The text explicitly states
"Implementation of agreed-upon risk responses is the responsibility of the risk owners."
2. Project Management Institute. (2017). The Standard for Program Management (4th ed.). Glossary
p. 171. Defines "Risk Owner" as "The person responsible for monitoring the risk and for selecting and implementing an appropriate risk response strategy."
3. Project Management Institute. (2017). A Guide to the Project Management Body of Knowledge (PMBOK® Guide) (6th ed.). Section 11.6
Implement Risk Responses
p. 453. This section states that a key aspect of this process is that "The project risk owners should be involved in developing the risk response and should be assigned the responsibility to implement the response."