Answer:
Cookies definitely obeys the law of conservation.`
Step-by-step explanation:
As, When Maria mixes up the ingredients, Water was also one among them
And, Initially When she was measuring the weight of Ingredients, Weight of Water was coming,
But,
When She baked the cookies , water from the cookies got evaporated , and thus weight coming was decreased finally.
Considering Cookies and Environment Whole as a system You can clearly say that they obeys Law of conservation of mass , As Water is present in Environment for now.