A positive correlation is when one variable increases and the other variable also increases. This means that as one variable goes up, the other variable tends to go up as well, indicating a direct relationship between the two.
Looking at the options provided:
- a states that one variable increases while the other decreases, which describes a negative correlation.
- b describes a situation where one variable decreases and the other increases, also indicative of a negative correlation.
- c mentions both variables decreasing which is again not a positive correlation.
- d none of the above, suggests that all previous answers are incorrect.
Therefore, the correct answer is none of the options listed. In a true positive correlation, both variables move in the same direction.