The correct answer is C. to.
The word “conform” means to act in accordance with a particular standard or set of rules. In this case, the speaker is telling the listener that they must act in accordance with the rules of the institute. The preposition “to” is used to indicate that the listener must follow the rules.
The other options are not correct because they do not convey the same meaning. The preposition “on” is used to indicate that something is based on or supported by something else. The preposition “of” is used to indicate that something is a part of or belongs to something else. The preposition “with” is used to indicate that something is associated with or connected to something else.
In conclusion, the correct answer is C. to. The other options are not correct because they do not convey the same meaning.