A pediatrician wishes to study how the average weight Y (in kilograms) of children changes during the first year of life. He plots these averages versus the age X (in months) and decides to fit a least-squares regression line to the data with X as the explanatory variable and Y as the response variable. He computes the following quantities: r = correlation between X and Y= 0.84 x = mean of the values of X = 5.69 y = mean of the values of Y = 6.26 S_x = standard deviation of the values of X = 3.23 s_y = standard deviation of the values of Y = 2.04 The slope of the least-squares line is: A) 0.53.B) 0.64. C) 0.84. D) 2.04.