While binding ur dbrm, one should specify explain = yes. After that, look out in ur plan_table, it will show u the path taken by optimizer.
we can tell some other paths that optimiser can choose(obviously, only if we modify the query) but i dont know whether one can get some list which will show all the paths that can be taken by optimizer.
you can get the accesspath chosen by optimizer for a query through PLAN_TABLE.
But all the possible paths will not be saved anywhere.
possible paths will be calculated by optimizer internally during BIND and select most optimum path and saves it.