Answer :
Answer:"The foreign secretary wanted to be certain that this message reached von Bernstorff" definitely implies a sense of urgency. "He made arrangements for it to be carried aboard a U-boat" does too—I'd say something's important if it requires its own boat.
Explanation:
The piece of textual evidence which best supports the inference that the message Zimmermann sent was very important is "The foreign secretary wanted to be certain that this message reached von Bernstorff" definitely implies a sense of urgency. "He made arrangements for it to be carried aboard a U-boat" does too—I'd say something's important if it requires its own boat.
What is Inference?
This refers to the use of deductions to come to a conclusion about a thing based on the available evidence.
With this in mind and from the given narration, there is the use of inference to show that the message Zimmermann sent was very important and this was showed in the fact there was a sense of emergency.
Read more about inference here:
https://brainly.com/question/1081576