Yes, a field can simultaneously be a primary and a foreign key. It is fairly common for a field to be a FK and part of a composite PK as in tblB below.
It is less common for a field to be a FK and an entire PK as in tblD. It is, however, perfectly legal.
Notice, in the second example, that the relationship between tblC and tblD is 1:1, not 1:N. Why must this be the case?