Which of the following would not terminate a properly formed joint tenancy between two co-tenants:

A: Foreclosure on a mortgage or trust deed secured by the interest of one joint tenant;
B: Death or permanent incapacity of either joint tenant;
C: One of the joint tenants signing a valid contract of sale to convey his interest in the property;
D: One of the joint tenants signing a deed of trust, creating a lien against his interest in the property.

Answer: D: One of the joint tenants signing a deed of trust, creating a lien against his interest in the property.