"DIe Lehrerin mag die Tassen" is also accepted. :)
why not "magst"?
Der Lehrer/die Lehrerin can be replaced by er/sie (3rd person, singular) so mag is correct here. Magst would be correct if you could replace the subject with du. Hope this helps...
Why not tasse ?
Marked incorrect! DIE
How do i know the teacher is male?