Which equation is true for transient equilibriunn?

$(\mathrm{\lambda }=\text{ disintegration constant; }\mathrm{t}=\text{ half-life })$

• A

  ${\mathrm{N}}_{\mathrm{A} }{\mathrm{\lambda }}_{\mathrm{A}}={\mathrm{N}}_{\mathrm{B}} {\mathrm{\lambda }}_{\mathrm{B}}$

• B

  ${\mathrm{N}}_{\mathrm{A}} {\mathrm{t}}_{ \mathrm{B}}= {\mathrm{N}}_{\mathrm{B}} {\mathrm{t}}_{\mathrm{A}}$

• C

  Both (a) and (b)

• D

  N_A t_A = N_B t_B