To solve this question, the user needs to know the subject-verb agreement rules in English grammar. In this sentence, "our thanks" is the subject and it is a plural noun. Therefore, the verb should be in the plural form as well.

Now, let's go through each option and explain why it is right or wrong:

A. "go": This option is the correct answer. "Go" is the plural form of the verb, and it agrees with the subject "our thanks."

B. "goes": This option is incorrect. "Goes" is the singular form of the verb, and it does not agree with the plural subject "our thanks."

C. "are": This option is incorrect. "Are" is a plural form of the verb "be," but it is not appropriate to use it in this sentence because "our thanks" is not a condition or state.

D. "is": This option is incorrect. "Is" is the singular form of the verb "be," and it does not agree with the plural subject "our thanks."

Therefore, the correct answer is:

The Answer is: A. go