In which set do all of the values make the inequality 2x - 1 < 10 true? a. {10, 15, 20} b. {5, 7, 9} c. {4, 6, 8} d. {2, 3, 4}

D. They are the only numbers small enough to stay under 10 when multiplied by 2 and subtracting 1. 

2x - 1 < 10 

Add 1 to both sides:
2x < 11

Divide both sides by 2:
x < 5.5

Answers must be smaller than 5.5, therefore option (D) is the answer.

 D. {2, 3, 4}