The structure of (S)-2-fluorobutane is best represented by :

Explanation:

• The structure for (S)-2-fluorobutane is characterized by the configuration where the fluorine (F) is attached to the second carbon of the butane chain. The S configuration indicates the relative orientation of the groups around the chiral carbon.
• In the image, Option c correctly shows the 3D structure with the fluorine in the correct position (behind the plane of the page) and the appropriate orientation of other substituents around the chiral center.

Thus, Option c represents the correct 3D structure of (S)-2-fluorobutane. ​