Ozonolysis of the given compound gives $\ce{I}$ , $\ce{II}$ , $\ce{III}$ and $\ce{IV}$.
- $\ce{I}$ and $\ce{II}$ are Homomers and have same configuration "S" and therefore identical (as shown in the figure).
- $\ce{III}$ and $\ce{IV}$ are achiral . Therefore , the total number of opticallyactive compounds formed after ozonolysis is $\ce{= 1}$.