The correct answer !

a. did you understand everything today?
b. no. i’m so confused.
a. so am i.
b. she doesn’t explain things very well. she goes too fast!
a. i know. and now we’re going to have a test!
you can infer that these two people are in a classroom because of the following evidence:

a. person "b" said someone "moves too fast".

b. person "a" said they were going to have a test.

c. they are not in a classroom.

d. both a & b are correct.