Which piece of textual evidence best supports the inference that the message Zimmermann sent was very important? Check all that apply.

“On January 16, 1917”
“a clear attempt to convince the Mexican government to help Germany in the war”
“Arthur Zimmermann . . . sent a telegram to Count von Bernstorff”
“The foreign secretary wanted to be certain that this message reached von Bernstorff”
“he made arrangements for it to be carried aboard a U-boat”