What is required to create a joint tenancy according to common law?

To create a joint tenancy under common law, the essential requirement is that the conveyance must be made to two or more persons at the same time through a single instrument. This creates what is known as "four unities": unity of time, unity of title, unity of interest, and unity of possession. Specifically, the unity of time means that all tenants must acquire their interests at the same moment, and unity of title indicates that they must all take under the same deed or will.

The requirement for a single instrument ensures that all parties are included in the same conveyance, preventing one person from having a separate or unilateral interest differing from the others. This simultaneous creation of interests is crucial for establishing the right of survivorship that characterizes joint tenancies, where upon the death of one tenant, their interest automatically passes to the surviving tenants.

In contrast, the other options do not fulfill these criteria. Conveyance to one person by a single instrument cannot create a joint tenancy because it lacks multiple parties. Similarly, conveying to multiple parties at different times or via separate instruments does not establish the necessary unity of time and title, thus failing to create a joint tenancy as required under common law.