OE


consummate, complete The blank is about the ambassador’s power. You have a same-direction signal (“hence”), and an important clue is that, due to this power, he “was able to draft and finalize the agreement unilaterally” (seems like a lot of power for a diplomat). A good fill-in would be something like a lot of or total. Tyrannical and dictatorial are a pair that goes too far, introducing a meaning (exercising total power, in a cruel way) that isn’t supported by any proof in the sentence. Tertiary (third) and enigmatic (mysterious) have no relationship.