The answer is B. Respected.
To emphasized their mutual hopes for the future
A. Policy, lmk if there’s anything else you need help on
Answer: U-boats were designed to make sure that messages being transported were secured.
Explanation: With the question and answer choices, it is a bit confusing at first. We see that, it’s talking about implications over explicit actualities, so we can remove the first and last choice about the message being important, while Zimmermann was looking for help. Both are explicitly stated in the excerpt, so it gives us a detailed account for why he was asking Mexico to assist Germany. It was not that stated that Mexico was expecting the message, and it was not hinted, since Germany is stated to only have gone through proper channels. They are trying to make sure they don't get caught, but one side is unaware of what is occurring. That leaves the U-boat choice, which seems like an accurate, implied statement from what is given. Nothing was suggested about the U-boat other than its level of transportation and method of delivery, but it is enough to infer. U-boats are stated to be for diplomatic channels and have to take certain routes, so the audience can think of its secrecy and security without being told.
