Which of the following compounds produces an optically inactive compound on hydrogenation $?$

The product of this reaction should be

What is the maximum number of stereoisomers possible for discodermolide?

The correct statements with respect to the above pair of reactions are that:
$(I)$ The reactions are stereospecific.
$(II)$ $(X)$ is erythro and $(Y)$ is threo isomer.
$(III)$ $(X)$ is threo and $(Y)$ is erythro isomer.
$(IV)$ Each of $(P)$ and $(Q)$ gives a mixture of $(X)$ and $(Y)$.

The most stable canonical structure of the given molecule is:

What are the configurations for $(i)$ and $(ii)$ respectively?