Fill in the blank with an appropriate word, phrase, or symbol(s).

(a) The value of r, the linear correlation coefficient, that represents the strongest positive correlation between two variables is  ___________ . 

(b) The value of r, the linear correlation coefficient, that represents the strongest negative correlation between two variables is  ___________ .

(c)  The value of r, the linear correlation coefficient, that represents no correlation between two variables is  ______________ .