Scientists are doing an experiment to test a new medicine. They have two groups of mice. Group A gets the medicine. Group B gets a placebo. After one week, they observe the mice. The scientists note that Group A is healthier than Group B. Then they write their conclusion: 'The new medicine helps mice stay healthy.'
According to the text, which sentence is an observation? (An observation is something that can be seen or measured directly.)
A)The new medicine helps mice stay healthy.
B)Group A is healthier than Group B.
C)The mice in Group A are more active.
D)The experiment proves the medicine works.