The coffee will increase alertness in David while driving.
Explanation:
A study by A.Nehlig shows that if 75 mg of coffee, i.e a cup of coffee, is taken every four hours then it helps in improving the mood of a person and also increases the alertness. However, if increased amount of coffee is consumed then it results in tense arousal like anxiety and nervousness. As David consumed two cups of coffee, which is more than the 75 mg uptake, so he is most likely to have an increased alertness while driving.
