A student performed four biological molecule tests on a milk sample. The tests and outcomes were: heating to 80^{\circ}C with Benedict’s solution produced a brick red colour. Adding Biuret solution produced a purple colour. Adding iodine solution produced an orange colour. Boiling with acid, then neutralisation, then heating to 80^{\circ}C with Benedict’s solution produced a brick red colour. Which biological molecules must be present in the milk?
- A1, 2 and 3
- B1 and 2 only
- C2 and 3 only
- D3 and 4