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