Which is true about the data?
a the slope of the best-fit line would be negative.
b there is a positive correlation.
c there is no correlation.
d there is a negative correlation.

Researchers were interested in whether relaxation training decreases the number of headaches a person experiences. they randomly assigned 20 participants to a control group or a relaxation training group and noted the change in number of headaches each group reported from the week before training to the week after training. which statistical analysis should be performed to answer the researchers' question?

Ineed i been stuck on this question since yesterday

Aquadratic equation in standard from is written ax^2= bx+c, where a,b and c are real numbers and a is not zero?