Explanation : In write through method, the word is written to the block in both the cache and main memory, in parallel and in write back method the word is written to the block in cache but actual update into the corresponding location in main memory only at specified intervals or under certain conditions. In Write Protected cache policy word cannot be modified or deleted.
In direct mapping block M of main memory maps into block M modulo n of the cache, where n is the total number of blocks in cache. So, option (A) is correct.
Explanation : only D2 is True because AD is key and present in both the tables. D1 is not always true because FD’s not given and if we take B->A and C->Athen it is lossy decomposition because no common attributes contain key from one of the table.