The verbs moods which would be best to combine in such an essay are:
C. the conditional and subjunctive moods.
Explanation:
The essay is about what life would be like if all wars were ended. Notice that this is a hypothetical essay. It is not about reality, not about what is, but about what could be. First, there is a condition that must be met: "if all wars were ended". To express such an idea - just like the sentence itself did -, we need the conditional mood. After establishing the condition, we can start talking about possibilities and wishes. That is what the subjunctive mood is for. Therefore, an essay that has such a theme would most likely combine the conditional and subjunctive moods.
