For the Reaction, A $\rarr$ B + C, the Rate Law Is Rate = K[A]

For the reaction, A $\rarr$ B + C, the rate law is rate = k[A]. If it takes 80.0 seconds for 70.0% of a 10.0 gram sample of A to be transformed into products, what is the value of the rate constant?

A) 0.00450 s^-1
B) 0.0290 s^-1
C) 0.00530 s^-1
D) 0.0150 s^-1
E) 5.40 s^-1