Which of the Following Observations Is an Example of a Positive

Multiple Choice

Which of the following observations is an example of a positive correlation?

A) When a group of 6-year-old children increase their physical activity level to 60 minutes a day,the children's muscle mass increases.
B) When teenage girls increase their intake of iron-rich foods,the percentage of the girls who have iron-deficiency decreases.
C) When older adults increase their daily intake of vitamin D,the percentage of the adults that develops infections decreases.
D) When a population consumes more fruits and vegetables,the percentage of people in that population with scurvy decreases.