Which one of the following is the correct step, in the procedure for making a temporary slide of human cheek cells? (1) Place the cheek cell scrapings in a watch glass containing water. (2) Place cheek cell scrapings in the centre of a clean slide. (3) Dip the toothpick, containing cheek cell scrapings, in the stain and then transfer to a clean slide. (4) Obtain cheek cells, directly on the slide, using its edge to scrape the inside of the cheek.