Atoms And Nuclei

At time t = 0, a material is composed of two radioactive atoms A and B, where N_A(0) = 2N_B(0). The decay constant of both kind of radioactive atoms is \(\lambda\). However, A disintegrates to B and B disintegrates to C. Which of the following figures represents the evolution of N_B(t) / N_B(0) with respect to time t?

[N_A (0) = No. of A atoms at t = 0

N_B (0) = No. of B atoms at t = 0]