Instruction 6.1 the Number of Column Centimetres of Classified Advertisements Appearing on Appearing

Instruction 6.1
The number of column centimetres of classified advertisements appearing on Mondays in a certain daily newspaper is normally distributed with population mean 320 and population standard deviation 20 cm.
-Referring to Instruction 6.1,a single Monday is chosen at random.State in which of the following ranges the number of column centimetres of classified advertisement is most likely to be

A) 310-330.
B) 330-350.
C) 320-340.
D) 300-320.