4. To what extent, if at all, do the following transactions constitute transfers subject to gift tax at the time of the transfer?
   1. Near Ds death, which as anticipated, occurred one year later, D gave an insurance policy on Ds life to Child C.
   2. D transferred securities to a trust, retaining the right to the income for Ds life and providing for payment of the corpus at Ds death to unrelated X or Xs estate.
   3. D transferred securities to a trust under the terms of which the income was to be paid to unrelated X for Xs life. Upon Ss death, the corpus was to be returned to D if D was living, and, if not, was to be paid over to unrelated Y or Ys estate.
   4. D transferred securities to a trust under the terms of which the income was to be paid to S for Ss life. Upon Ss death, the remainder was to go to X or Xs estate. However, D retained an unlimited right to alter the terms of the trust in any manner.