Only Answer B is always correct. While the implode function can be used to convert an array into a string—a prerequisite of being able to store it in a cookie—it cannot guarantee that you’ll be able to reconstruct the array at a later date the way serialize() can. Storing an array in a cookie may not be a good idea because browsers only allow a limited amount of storage space for each cookie, but that’s not always the case—you should be able to store relatively small arrays without much in the way of problems.