Answer is: A. adding heat to the product mixture.
Balanced chemical reaction:
CO(g) + 3H₂(g) ⇄ CH₄(g) + H₂O(g); ΔH = -206.1 kJ.
This reaction is exothermic, which means that heat is released.
According to Le Chatelier's principle when the reaction is exothermic heat is included as a product and when the temperature increased, the heat of the system increase, so the system consume some of that heat by shifting the equilibrium to the left.
Solution: Sentence D is a scientific statement.
Scientific statement is a statement that defines the science behind any situation. There should be any experimental result or observation to state any scientific statement. Also, the statement should be accepted by considering other scientific aspects.
Here, statement A can not be a scientific statement as different aromas of cooked food are liked by different people. Any one can find aroma of cooked food in copper better than the ceramic pot.
Thus, the statement can be proved wrong easily.
Statement B can not be a scientific statement as people can find the taste of normal water (without ice cubes) better than the ice cold water.
Statement C is not a scientific statement as there is no science behind watching baseball or ice hockey, it depends on the liking of today's people.
Statement D is a scientific statement because this can be scientifically proved.
Enzymes are needed to digest food in stomach