teacher stood up,and______ some students.The teacher stood up,and______ some students.The teacher stood up,______ some students and came into the classroom.A following B followed C to follow D follow

Both answers should be B followed.
The teacher stood up, and followed some students.
Followed is used because from the word "and", we can see that stood up and followed are two separated actions. The teacher finished one action before starting another.
The teacher stood up, followed some students and came into the classroom.
Same reason again. The coma between stood up and followed and the word "and" before came indicates that they are three separated actions and representing there are no links between these actions.
It would have been a different case if the coma is removed on the second line.
The teacher stood up ____________ some students and came into the classroom.
In this case, the answer would be A following.
This is because the -ing form is often used after a preposition.

BA

The teacher stood up,and followed some students.
and 前后一致
The teacher stood up,following some students and came into the classroom
following 形容词,修饰名词

B followed 、A following