Which one of the following words or phrases may be a clue that a sentence is inferring cause and effect?

The questions on the test are multiple choice and are derived from the state driver’s manual. you should read the manual thoroughly before attempting the written test. what is the best way to paraphrase this part of the passage? a) it is important to read and memorize the driver's manual. b) the written test questions come directly from the driver's manual. c) the written test questions may or may not come from the driver's manual. d) it is important to read the driver's manual carefully since many test questions come from it.