To increase the number of applier processes on a logical standby database, the following changes can be made:

C: Increasing the value for theMAX_SERVERSSQL apply parameter would allow for more applier processes to be initiated, assuming that system resources permit.

D: Increasing thePARALLEL_MAX_SERVERSinitialization parameter would allow for more parallel execution processes, which can be used by SQL apply to increase the number of applier processes.

Option A is incorrect as decreasing the number of archiver processes will not necessarily increase the number of applier processes; these are unrelated components.

Option B is incorrect because the 'FREPARER' processes do not exist, it seems to be a typographical error, and the 'REPARER' is not a valid Oracle process or parameter.

Option E is incorrect because theRECOVERY_PARALLELISMparameter controls the number of processes used for instance recovery and media recovery, not for SQL apply.