A Pion Lives 26 Ns in Its Rest Frame,but an Observer

Multiple Choice

A pion lives 26 ns in its rest frame,but an observer in a laboratory in which the particle moves at a speed of 2.7 $\times$ 10⁸ m/s says the particle lived

A) 11 ns
B) 15 ns
C) 43 ns
D) 60 ns
E) 79 ns