The main function of the operating system is to control both the hardware and software components of a computer. It acts as an intermediary, managing hardware resources and allowing software applications to run and interact with the computer's hardware. While organizing files and folders is a task performed by the operating system, its primary role is to facilitate communication between software and hardware, ensuring the computer functions properly.

1. Slide transitions are animation-like effects that occur when you move from one slide to another during an MSPowerPoint 2010 slide show.

2. Slide transitions apply whole-slide and can be used to make slide shows more vibrant and attractive.

Among the given statements about for loops, the one that is NOT true is that they are used to replace user input while loops. While for loops are typically used for iterations with a known count and are less likely to result in an infinite loop if used correctly, they do not specifically replace user input while loops.