Particles M and N move along a line with constant accelerations aM(t)=4 m/s2 and aN(t)=2 m/s2, respectively. At t=0, both particles are at the origin; particle M is at rest, while particle N has velocity 6 m/s directed in the positive direction. Determine the time t (in seconds) when the particles next occupy the same position.
(a) 3
(b) 12
(c) 6
(d) 8