Final answer:
In the given sentence, the word 'reciprocate' suggests that there is a mutual level of respect between the diplomats, as one invites the other to a concert as a gesture of returned hospitality.
Step-by-step explanation:
The word reciprocate in the context of the sentence concerning the diplomat's actions suggests that there is a mutual level of respect and a formal relationship between the diplomats. Reciprocating hospitality by inviting the counterpart to a concert is an example of balanced reciprocity, where an act of kindness or generosity is returned in a similar way, thereby affirming and strengthening the relationship between the individuals or entities involved.
Diplomacy often involves such exchanges to maintain positive international relations. The act of reciprocation here implies that the diplomats are acknowledging each other's gestures and maintaining a courteous and cooperative relationship, which aligns with the option A that they are respectful of each other.