Answer : The correct answer for rate of consumption of B = 
Dynamic equilibrium :
Dynamic equilibrium is state of equilibrium where reactants convert to product and product converts to reactant at equal and constant rate . The concentration may not be same but rate will be same .
This occurs when reaction is reversible type .
The hypothetical reaction is :
A ↔ B where ↔ represents reversible reaction
Rate of consumption of A is given as :
![R(a) = k * \frac{d[A]}{dt}](https://tex.z-dn.net/?f=%20R%28a%29%20%3D%20k%20%2A%20%5Cfrac%7Bd%5BA%5D%7D%7Bdt%7D%20%20)
Where . R(a) = rate of consumption of A
k = rate constant
[A] = concentration of A
t= time
Rate for consumption of B =
![R (b)= k * \frac{d[B]}{dt}](https://tex.z-dn.net/?f=%20R%20%28b%29%3D%20k%20%2A%20%5Cfrac%7Bd%5BB%5D%7D%7Bdt%7D%20%20)
R(b) = rate of consumption of B , [B] is concentration of B
Since the reaction is at dynamic equilibrium , so :
Rate of consumption of A = rate of consumption of B
Given : rate of consumption of A = 
Hence rate of consumption of B = 