All the answers on this question list two things happening. That should tell you that both things need to have a big effect for an answer to be correct.
In several wrong answers, only one of the two elements has an effect. That’s not enough to force R to be a journalism major.
For instance, D and E are wrong. We already knew that M speaks on friendship, so half of these answers add no information.
A makes M a geology major. That has little automatic effect on the setup. It just makes N a geology major in liberty. There are two history major spots left, so P can fill one without forcing R to be a journalism major.
The first part of B is good. If O is a geology major, then O and N fill both geology major spots. This forces M to be a history major:
But, the second part of this answer just repeats this deduction. It says M is a history major. We already knew that, based on the first part. This answer doesn’t force R to be a journalism major.
C is CORRECT. Let’s extend the diagram I made for B. If P is a history major, then they must be in L. This forces R to take the journalism major:
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