A table is in $2$nd normal form if$\_\_\_\_\_\_\_\_.$

A$.$ it is in $1$st normal form and all fields in the table refer to or describe the primary key.

B$.$ it is in $1$st normal form and all transitive dependencies have been removed.

C$.$ it is in $1$st normal form and all fields are single valued.

D$.$ it is in $1$st normal form and every row is unique.