A certain liquid drug is marketed in bottles containing a nominal 20ml of drug. Tests on a large number of bottles indicate that the volume of liquid in each bottle is distributed normally with mean 20.42ml and standard deviation 0.429ml. If the capacity of the bottles is normally distributed with a mean of 21.77ml and standard deviation 0.210ml, estimate what percentage of bottles will overflow during filling.
a) 12.5%
b) 25%
c) 37.5%
d) 50%