Probability doubt

[happy]

E(X|Y) = E(E(X|Y,Z))
E(X|Y) = E(E(X|Y,Z)|Y)  

which one is correct?

[AdityaGarg13]

Is it second one???

[Sachin Sehgal]

The answer is B. https://stats.stackexchange.com/questions/95947/a-generalization-of-the-law-of-iterated-expectations?_e_pi_=7%2CPAGE_ID10%2C5141375047

[Rajesh]

From where this ques. is?

[happy]

thanks

[happy]

This question didn't asked directly, but this concept used in my probability question