The graph indicates the number of students in a class for each blood group. What conclusion can be drawn about blood groups from the graph?
- ABlood groups are an example of continuous variation caused by genes and the environment.
- BBlood groups are an example of continuous variation caused by genes only.
- CBlood groups are an example of discontinuous variation caused by genes and the environment.
- DBlood groups are an example of discontinuous variation caused by genes only.