Final answer:
The statement that 'Folding in peanut butter must be done' is true for the peanut butter cookie recipe, while the others are incorrect.
Step-by-step explanation:
The peanut butter cookie passage provides instructions for making cookies, and it asks which statements about the passage are true. According to the passage, you need to beat egg whites until foamy and then until stiff peaks form, which involves more than simply stirring vigorously; it requires whisking them until they reach a certain texture. Also, it specifies that you must gently fold in the peanut butter into the beaten egg whites, which is different from just mixing it in, as folding helps to maintain the air incorporated into the egg whites. The cookies should be baked in an oven at 350 degrees F, not in a microwave oven, and they should be allowed to cool on a cookie sheet rather than a baking rack, making them less likely to break due to their fragility.