Mr. Jacob, who is terminally ill, writes a will transferring all his assets to his daughter Silvia, in the event of his death. The doctors say that Mr. Jacob will live for about six months. A day after the will is written, Silvia wishes to transfer her expected inheritance to her son, Jacob Jr. This assignment will be ________.
A) valid
B) conditionally valid
C) invalid
D) re-assignable by Jacob Jr.