B is correct provided that there is no cart attribute in page and request scopes. Given the literal interpretation of exam questions, I would have to agree that D is the only correct choice given the specific language of the question. When I have doubts about a question like this, I choose the correct answers first and then try to find the "best answer" to fill in the requirement of choosing 2. I came up with B and D without peeking at the answer first by using this technique. I hope that this helps.