Which statement is not correct?

a. A primary element of a contingency plan is the quantification of recovery objectives in RTO and RPO, given the organization’s strategic priorities.

b. The only points of failure of a database system are the availability of database functionality and the availability of the data themselves.

c. The manual failover of DBMS functionality is a simple and not very expensive solution to guarantee the availability of DBMS functionality in the case of a calamity.

d. Rolling upgrades are an example of how to avoid downtime in a cluster computing set-up.