Sam's teacher was very impressed because he had created a logical presentation. Which of the following probably describes Sam's presentation?

Which of the following sentences requires a colon to be correct? a. in his vacation suitcase, jonathan packed two pairs of pants, four shirts, his swimsuit, and his favorite pajamas. b. when she decided to write a letter, she grabbed her pen, paper, stamps, and address book. c. the new dessert recipe called for equal parts of sugar, cream, peanut butter, and crushed pecans. d. she gathered all of her ingredients to make a smoothie strawberries, blueberries, bananas, and yogurt.