Q: Exemplified by a lit match bursting into flame or the process that forms fossil fuels, chemical reactions vary greatly in terms of what?


Read this paragraph and choose the correct option from the provided answers:

Chemical reactions vary widely in the speeds with which they occur. Some reactions occur very quickly. If a lighted match is brought in contact with lighter fluid or another flammable liquid, it erupts into flame instantly and burns fast. Other reactions occur very slowly. A container of milk in the refrigerator will be good to drink for weeks before it begins to turn sour. Millions of years were required for dead plants under Earth’s surface to accumulate and eventually turn into fossil fuels such as coal and oil.

 Choices:

- duration

- density

- power

- speed


A:
speed