D) Cassandra's best option would probably be carrying a notebook and immediately recording all of her transactions in it. Since she does not like to do a lot of heavy thinking when she gets home, and tends to lose pieces of paper, this method is ideal because it would allow her to consolidate all her purchase records in one notebook, eliminating the need to carry receipts, and recording them immediately will make it so she can relax when she gets home. Perhaps once a month, she can compile all of her notebook activity into a computer program and reconcile it to her bank statements.