Answer : 1. "Cooking of Food"
Explanation :

Answer: A) A & B Explanation: A) Cooking of Food  ------ Chemical Change B) Digestion of Food ----- Chemical Change C) Freezing of water ----- Physical Change D) Water is heated up ---- Physical Change because here the chemical composition of the substance changes in A & B only.   Since we know that, If the chemical composition is changing then it is a chemical change and if the chemical composition is remaining the same, then it is a physical change.