Final answer:
To achieve the least volume using rollers, use large rollers positioned flat against the scalp and wrap hair smoothly without tension. Ensure hair dries completely before gently brushing to reduce volume further.
Step-by-step explanation:
The recommendation for achieving the least volume in hair when using rollers is to choose large rollers and to place them so that they sit completely flat against the head. This would typically involve rolling the hair down from the ends towards the scalp in a manner that does not elevate the hair much from the head. For even less volume, one could start by applying a smoothing product to damp hair and then using the large rollers, making sure the hair is wrapped smoothly and without any tension.
It is important to ensure the hair is fully dried before removing the rollers. Once the hair is dry and the rollers are carefully taken out, you may gently brush the hair to further reduce volume and smooth out the style.