An isothermal aqueous phase reversible reaction, P R, is to be carried out in a mixed flow reactor. The reaction rate in k.mole/m3 .h is given by, r = 0.5CP - 0.125CR. A stream containing only P enters the reactor. The residence time required (in hours) for 40% conversion of P is

• A. 0.80
• B. 1.33
• C. 1.60
• D. 2.67