The Attractive Force Between Protons and Neutrons in the Nucleus $\pi$

Multiple Choice

The attractive force between protons and neutrons in the nucleus is brought about by the exchange of a virtual pi-meson (m $\pi$ = 140 MeV/c2) .Estimate the longest time a virtual $\pi$ 0 can exist, in accordance with the uncertainty principle .(1 eV = 1.6 * 10-19 J.)

A) 2.4 * 10-24 s
B) 6.9 * 10-27 s
C) 3.3 * 10-18 s
D) 2.4 * 10-21 s
E) 1.6 * 10-19 s