Final answer:
Full title and possession of real estate in a will typically pass to the beneficiary, in this case to Xavier's niece Annette, after probate court approval.
Step-by-step explanation:
The transfer of real estate ownership after someone's death is a process that involves legal considerations and may vary depending on the conditions set out in the deceased's will. In the scenario provided, where Xavier devised his real estate to his niece Annette by his will, full title and possession of the property would typically pass to Annette after probate court approval. This is because the probate process is necessary to validate the will, settle any debts of the estate, and legally transfer assets to the rightful beneficiaries.
Options such as passing immediately upon death, upon reaching a certain age, or upon payment of inheritance taxes are not typically the triggers for the transfer of ownership. These factors may influence aspects of the inheritance process, but they do not determine when the actual title and possession are transferred. Therefore, the correct answer is that full title and possession pass to his niece after probate court approval.