In OCR, each pixel is an estimate of how _______ the corresponding area is.

Posts and the topic statement make up a(n) ________ on a message board

A) thread B) COPPA C) summary thread D) opening post

During the late 1960s, ARPA created one of the country's first wide area packet-switched networks, the ____________________.

Fill in the blank(s) with the appropriate word(s).