Given a negative correlation was found between number of weeks of physical therapy and pain level and corresponding slope was found to be equal to -1.50; one would conclude that: a. for every week of physical therapy pain would be expected to reduce by 1.50 points b. for every week of physical therapy the error in pain measurement would be 1.50 O for every week of physical therapy pain would increase or decrease by 1.50 points Od that the physical therapy was not effective