<span>Validation of electronic signatures was designed to encourage a paperless society.</span>
The answer is (a.) DOS
DOS stands for Disk Operating System. MS-DOS is the operating system which has a command interface similar to the command prompt of Windows 7 and Windows 8. Among the options, DOS is the only OS which is has a command line interface. Others have graphics.
The client will attempt to renew halfway through the time of the lease.
