Answer : Application whitelisting
Explanation : an application whitelisting is the security approach used by organisations and administrators to secure the organisation devices and system. The application whitelisting works in such a way that, case administrator powers to restrict users or employees from using any malicious or any other application which is not allowed to be used in the organisation . the administrator will use the application whitelisting to only allowed those applications for the employees to access which the administrator wants to . Therefore the apps not listed in the The whitelist of applications are not allowed to be used in the devices provided by the organisation . Hence , to increase the security of the 20 Android tablets purchase by the organisation "Application whitelisting" will be the best approach to do so , by allowing only those apps which are allowed by the organisation to be installed and worked upon in those tablets . Above provided question is answered and explained feel free to ask any questions in the comments section below.