It will ve enough just giving the correct answer(Please as FAST as possible) You don't need to write explanation.

4- SaaS refers to: a) easy-to-use software tools for displaying Web pages. b) managing combinations of applications, networks, systems, storage, and security as well as providing Web site and systems performance monitoring to subscribers over the Internet. c) supplying online access over networks to storage devices and storage area network technology. d) self-contained services that communicate with each other to create a working software application. e) hosting and managing access to software applications delivered over the Internet to clients on a subscription basis