$$n$$ samples of same liquid with masses $$m, 2m, 3m, \ldots, nm$$ at temperatures $$t, 2t, 3t, \ldots, nt$$ are mixed in an isolated system. The resultant temperature of the mixture is

A

$$nt$$

B

$$\frac{n(n + 1)t}{2}$$

C

$$\frac{n(n + 1)(2n + 1)t}{6}$$

D

$$\frac{(2n + 1)t}{3}$$