Select the correct statement from among the following: The diameter of a certain rod is normally distributed with a mean of 1.20". The proportion of rods with diameters less than 1.0" is 

a. greater than the proportion of diameters larger than 1.2". 

b. greater than 50%. 

c. equal to the proportion of diameters larger than 1.40". 

d. less than the proportion of diameters smaller than 0.5.

 what is the correct answer and why?