Suppose you make a telephone call to a friend or relative in Mexico or in France. Suppose you send a letter to China using a stamp from the United States. Learn about international agreements that make it possible for your tele- phone call or letter to reach its destination. Find information about the Universal Postal Union or the International Telecommunications Union.​

the answer to fill in the blank in this question would be the word resource, it is defined as the money, material or people (since human resource is a very valuable good) that a company or a person has at disposition (meaning they can use the resource as they see fit), to be able to complete a task or achieve a goal.  

according to this text from the preamble to the declaration, who gives men their unalienable rights?