For a first order reaction , `A to` Products, the concentrations of A changes from 0.1 M to 0.025 M in 40 minutes. The rate of reaction when the concentration of A is 0.01 M is:
A. `1.73 xx 10^(-5)` M/min
B. `3.47 xx 10^(-4)` M/min
C. `3.47 xx 10^(-5)` M/min
D. `1.73 xx 10^(-10)` M/min