State whether or not a trust is created in each of the following situations:
a. A declares herself trustee of ‘‘the bulk of my securities'' in trust for B.
b. A, the owner of Blackacre, purports to convey to B in trust for C ‘‘a small part'' of Blackacre.
c. A owns ten bonds. He declares himself trustee for B of such five of the bonds as B may select at any time within a month.
d. A deposits $100,000 in a savings bank. He declares himself trustee of the deposit in trust to pay B $50,000 out of the deposit, reserving the power to withdraw from the deposit any amounts not in excess of $50,000.