The best answer would be E.
Both are examples of food consumption:)
For the first blank it would be: Lock
&
For the second blank it would be: Key
They must be non-toxic ie not chemicals that could poison the customers because of the potential risk of contaminating things which can come into contact with the food like say cutting boards, dishes, utensils, pots, pans and any other similar items.
The law reduced acid rain and improved public health by dramatically reducing emissions of sulfur dioxide (SO2) and oxides of nitrogen (NOx).
I guess I correct. Can anyone just tell me if I am correct?