Which of the following best illustrates a pair of sentences that are joined by an understood relationship?
a. i don't understand a word you said. have you taken a course in english literature?
b. luke put three dollars into the office football pool. he was looking forward to vacation.
c. it rained for ten days and ten nights. grandmother grady called a company to drill a well.
d. detective smiley scanned the dim hallway. he pulled his pistol from its holster.