__________ represent waiting lines; insertions are made at the back (also called the tail) and deletions are made from the front (also called the head) of a __________.

Which of the following is a good candidate for a primary key?

A) A student ID in a college registration database B) A postal code in an address database C) A car model in a Motor Vehicle Department database D) A street name in an address database

____ attacks can be successful when the ciphertext consists of relatively few characters.

A. Correlation B. Man-in-the-middle C. Dictionary D. Timing