Consider the following statements related to the pore pressure parameters, A and B: P. A always lies between 0 and 1.0 
Q. A can be less than 0 or greater than 1.0 
R. B always lies between 0 and 1.0 
S. B can be less than 0 or greater than 1.0 
For these statements, which one of the following options is correct?