A student tested one milk sample for biological molecules. The outcomes of the tests were: • When heated to $80\,^{\circ}\text{C}$ with Benedict’s solution, a red colour was produced. • After boiling with acid, then neutralising, and then heating to $80\,^{\circ}\text{C}$ with Benedict’s solution, a red colour was also produced. • On adding Biuret solution, the colour became purple. • On adding iodine solution, the colour became yellow. Which biological molecules have to be present in the milk?
- A1, 2 and 3
- B1 and 2 only
- C2 and 3 only
- D3 and 4