Is any piece of computer hardware equipment which converts information into human-readable form.
a.output device
b.input device
c.software
d.operating system

It is a form of computer memory that can be read and changed in any order, typically used to store working data and machine code.
a.ram
b.dvd
c.usb
d.rom

It is designed to supersede cd format(sometimes explained as "digital video disc" or "digital versatile disc".
a.dvd
b.cd
c.usb
d.rom

Are typically removable and rewritable, and physically much smaller than optical disc.
a.rom
b.usb
c.dvd
d.cd

Is a digital optical disc data storage format.
a.cd
b.dvd
c.usb
d.ram​