When a tenant remains in possession after the termination of the lease without permission of the landlord, the landlord may treat the tenant as either a trespasser or a tenant. Until the landlord elects to do one or the other, there exists a $\_\_\_\_\_\_\_\_\_\_.$

a$.$ tenancy at sufferance

b$.$ tenancy at will

c$.$ tenancy for years

d$.$ tenancy from year to year