Mrs Ang went to the wet market. At the fresh fish stall, she ordered five slices of mackerel. The fish monger proceeded to cut five slices from the whole mackerel, bagged it, and weighed it to determine price. Mrs Ang then changed her mind and told the fish monger that she wanted prawns instead. Using the relevant section of the Sale of Goods Act Singapore,

Can you please suggest me that Mrs Ang can change her mind at that point of time?