When a router boots, what is the default order to locate the Cisco IOS if there is no boot system command?

ROM, TFTP server, flash 
flash, TFTP server, ROM 
flash, NVRAM, TFTP server 
NVRAM, TFTP server, flash 

ccna 2 final Exam Question And Answers 

OWhen a router boots, what is the default order to locate the Cisco IOS if there is no boot system command?