Answer:A
Step-by-step explanation:this is not true
Answer:
c. observational study
Step-by-step explanation:
<em>Researchers compare the rates of autism for children who did and did not receive the standard measles-mumps-rubella vaccine, to see if the vaccine might be responsible for autism in some children.</em>
This study design in the above scenario is observational study because the researcher are obviously observing whether the vaccine is affecting the children. Note that Observational study is like experiment which attempts to understand the cause and effect relationships on a subject.
-9 is a rattional number because it is an integer and it can be squared.
The answer is (3,0). Hope this helps!(:
