Answer:
a .energy added to start a reaction
Answer: Specie
Explanation:
The basic unit of classification of living things is species. species is the smallest unit containing members which have the largest number of features in common and usually interbreed among themselves.
Thus, the group of deer describes a specie since they can interbreed freely and are similar in characteristic features.
The first box should be atoms, the second element, and the third box compound.