Answer:B)Control File
D)Archive Log-files
Explanation:
Control file is a file which holds the status of the databases elements such as names, location,online redo files, etc in binary form. This requires the multiplexing by collecting all these database elements into one encapsulated unit.
Archive log-files are those file which holds the redo files in the offline ports which contain the elements.The also form a single group for the safety by multiplexing method.