Final answer:
The strongest correlation coefficient among the options is b. -.81, which indicates a strong negative relationship. Option c is invalid as it exceeds the possible range for correlation coefficients, and option a is a strong positive correlation but still weaker compared to option b.
Step-by-step explanation:
The correlation coefficient that indicates the strongest relationship between two variables among the provided options is b. -.81. The correlation coefficient, represented with the letter r, can range from -1 to +1. Negative and positive values indicate the direction of the relationship, with -1 being a perfect negative correlation and +1 being a perfect positive correlation. A value of 0 indicates no correlation. Option c. +1.25 is not a valid correlation coefficient since it falls outside the range of -1 to +1. Even though option a. +.75 is a strong positive correlation, option b. -.81 indicates a stronger, yet negative relationship. The closer the absolute value of the correlation coefficient is to 1, regardless of the sign, the stronger the relationship between two variables.