Purposeful and decisive are the options that best describe Romeo's demeanor during his last action. Answer A is correct.
I think that option A is correct because in spite of the fact that Romeo is sad and hysterical in the last act, he does not hesitate and he decisivly kill himself.
In the last act, Romeo thinks that Juliet is dead. He feels desolate and devastated becouse of that. Consequently, he says his goodbyes to the world, takes the poison intentionaly, kisses Juliet and then he dies.