The type of communication that the teacher has in the classroom, is termed as

a. Interpersonal

b. Mass communication

c. Group communication

d. Face-to-face communication

It's definitely not a mass communication: it does not include mass media.

It's actually all the other choices:

a. Interpersonal (between people)

c. Group communication (in a group)

d. Face-to-face communication (not mediated by technology)

I would choose the option of Group communication, as it's its more visible trait, but technically, all those options are correct!