Which type of system requires a regular backup of files?

In a word processing program, such as microsoft word, which feature to you choose the desired picture enhancement?

In excel - calculate the actual increase/decrease from first quarter to the second quarter then subtract subtract first quarter value from second quarter total then divide result by first quarter value

Which of the following is not an enhancement to the standard wiki to make it more attractive for corporations? encryptionwork spacespermission toolspredictive text