The answer to your question is c.invented because it's a past participle.
A is the answer to your question
Hamlet does accept the duel however, for two reasons: firstly, it offers him an opportunity to resolve his conflict with Laertes, whose forgiveness he craves (a fencing duel with foils - blunted blades - is a courtly sport after all, and chiefly an exercise in male bonding).
Secondly, and more significantly, Hamlet is world-weary and ready to succumb to any outside agency.
Consider the following conditional sentences, and pay close attention to the conditional verbs in each of them:
If my cousin had been just a little taller, he could have been a basketball player.
If I had enough money, I would travel around the world.
If Alex finishes his essay, he will come over tomorrow.
After looking at how a conditional verb is used in a sentence. I would say that Conditional is the correct answer.
