Position Isomerism:
- The molecular formula C5H12O indicates the presence of five carbon atoms, twelve hydrogen atoms, and one oxygen atom.
- Position isomerism can occur in this case when the atoms are arranged differently within the molecule, leading to different structural isomers.

Optical Isomerism:
- If the molecule has a chiral center or an asymmetric carbon atom, it can exhibit optical isomerism.
- In the case of C5H12O, if the arrangement of atoms around a carbon atom results in non-superimposable mirror images, optical isomerism is possible.

Functional Isomerism:
- Functional isomerism occurs when compounds have the same molecular formula but different functional groups.
- For C5H12O, functional isomerism could arise if different functional groups are present in various structural isomers.

All of These:
- The molecular formula C5H12O has the potential to exhibit position isomerism, optical isomerism, and functional isomerism.
- By exploring various structural arrangements and functional groups, different isomers with distinct properties can be formed.
In conclusion, the molecular formula C5H12O has the flexibility to give rise to different isomers due to position, optical, and functional variations. This diversity in isomerism highlights the importance of structural arrangements and functional groups in determining the properties and behavior of organic compounds.