What property rights or easement types are created in the following examples: a. A tells B that B can drive across A's property to drop off a load of firewood on B's property. b. A tells B that B can drive across A's property so that B can build a house on B's property, and then B commences construction. c. A gives B the right to remove timber from A's land. d. A has B come to A's house for dinner.