Computer organisation

Question

I know that correct answer is none of these 

But I need explanation with answer

Answer 1

RAM memories allows simultaneous read and write operations.

read/write memory A type of memory that, in normal operation, allows the user to access (read from) or alter (write to) individual storage locations within the device. The choice of read or write operation is normally determined by a read/write signal applied to the device. RAM devices are typical read/write memories.

Read/write means capable of being displayed (read) and modified (written to). Most objects (disks, files, directories) are read/write, but operating systems also allow you to protect objects with a read-only attribute that prevents other users from modifying the object.

Read-write memory is a type of computer memory that may be relatively easily written to as well as read from, that is, using electrical signalling normally associated with running software, and without other physical processes (unlike ROM or "read-only memory" and distinct from EEPROM).