Given the following passage  "In the 1970s, computer engineers at research institutions throughout the United States began to link their computers together using telecommunications technology. The effort was funded by ARPA (now DARPA), and the computer network that resulted was called the ARPANET. The technologies that made the Arpanet possible spread and evolved.",  answer the following question. Note that the answer is present within the text.  Question: To extend or apply to a surface in an even layer is called what verb?
A:
spread