are the leading causes of death worldwide
If he studied a small sample it wouldn't be a representative sample. since he got such a large sample there is a chance most likely all organisms follow the rules of evolution.
Answer:
they carry out experiments to understand it
Explanation:
Scientists raise hypotheses which are tested by experiments made under controlled conditions in order to explain a particular topic. When a hypothesis is confirmed by the experimental data, the evidence obtained from this experiment provides the basis to increase the scientific knowledge about a particular issue. In consequence, experimentation can be considered as a critical step in the scientific method and research aims to advance knowledge of a particular phenomenon by confirming a hypothesis, which must be testable (i.e. verifiable as a result of further experimentations).
I think it's oxygen and water because they are the substance for cellular respiration.
