What Should a Controller Do After a Data Subject Opts

What should a controller do after a data subject opts out of a direct marketing activity?

A) Without exception, securely delete all personal data relating to the data subject.
B) Without undue delay, provide information to the data subject on the action that will be taken.
C) Refrain from processing personal data relating to the data subject for the relevant type of communication.
D) Take reasonable steps to inform third-party recipients that the data subject's personal data should be deleted and no longer processed.