The Half-Life of a Muon Is 2 $\mu$ S as Measured in a Stationary Reference Frame

Multiple Choice

The half-life of a muon is 2.20 $\mu$ s as measured in a stationary reference frame.What is the half life of the muon (in $\mu$ s) when it is moving with a speed of v = 0.800 c?

A) 8.13
B) 2.75
C) 3.67
D) 15.8
E) 1.32