The Initial Concentration of Reactant in a First- Order Reaction

The initial concentration of reactant in a first- order reaction is 0.27 M. The rate constant for the reaction is 0.75 s^{- 1}. What is the concentration (mol/L) of reactant after 1.5 s?

A) 1.7
B) 2.0 × 10^{- 2}
C) 3.8
D) 0.135
E) 8.8 × 10^{- 2}