A graph between t₁/₂ and concentration for nth-order reaction is a straight line. The reaction of this nature is completed 50% in 10 minutes when concentration is 2 mol/L. This is decomposed 50% in t minutes at 4 mol/L. Then n and t are respectively:

A) 0, 20 min
B) 1, 10 min
C) 1, 20 min
D) 0, 5 min