Option B.

Option B is a much better default than Option C. Option C requires that every entity bean go back and forth between the pooled and the ready state, between every transaction. In the (very common) case that you are using a working set of entity beans, this is just busy work, which has a measurable performance overhead.

Basically, we are trying to make the defaults have the best performance for the common use cases and allow the user to change the defaults when their usage patterns differ. Caching is an option, specifiable in the deployment descriptor (and by default Option A style caching is disabled, since it cannot be assumed that by default the database is unshared).