In the estimated regression equation Y = b1X + b0 if the X,Y correlation was a positive number then ...

1. both b0 and b1 must also be positive

2. both b0 and b1 may be either positive or negative

3. b0 must also be positive, though b1 could be either positive or negative

4. b1 must also be positive, though b0 could be either positive or negative