The total number of stereosiomers that can exist for M is

Answer

2

Explanation

M has two dissimilar chiral carbon atoms, therefore, total number of stereoisomers theoretically possible `=2^(2)=4`.

But due to the presence of a smal bridge, the structure becomes rigid. As a result, rotation is not possible and the two chiral carbon atoms more together and thus behave as one chiral carbon. Consequently, the molecule M exists in two stereoisomers.