Answer:The teacher impressed on us the value of discipline.
Explanation: :)
The meaning of the sentence is the teacher tried to put some value of discipline in students. The prepositions are the words which connect a noun or pronoun to a verb or an adjective.
In, On, With, At, By, From, etc. are the examples of the adjectives. In the given sentence, on is used as preposition to describe that the teacher impressed value of discipline on students. Hence, the correct answer is 'on.'