This is a test of commonsense with single/multi-choices. Complete the next sentence:

How to fit a roller blind
Determine the placement of the blind.
Although roller blinds are typically installed inside of the window frame, it can also sit outside of the window frame or above the window. The location of the blind is personal preference.

Select from:
1). If you have a spot marked, you can tell it is going to be just outside of the frame, as this will determine whether you have the correct positioning for the blind. If you intend to install the blind on another horizontal object, such as a wall, then you may require an outer blind..
2). Make sure that the blinds are centered around the edge of the frame and are in the proper position. You do not want to accidentally drill a hole or otherwise damage the blind..
3). Make sure that you determine where you would like to install the blind before buying the blind. Hold the blind up to the window to visually see where you would like to secure the brackets..
4). In some cases, the blind will be placed above or below the window frame, otherwise it will be hanging beneath. However, look for the location of the blind you need for the best approach..
The answer is:
3).