A Reaction Is First Order in A $\times$ 10^-3 S^-1, What Is the Half-Life (T_1/2) of the Reaction

A reaction is first order in A. If the rate constant of the reaction is 3.45 $\times$ 10^-3 s^-1, what is the half-life (t_1/2) of the reaction?

A) 4.98 $\times$ 10^-3 s
B) 200 s
C) 3.45 $\times$ 10^-3 s
D) 100 s
E) 1.73 $\times$ 10^-3 s