test series

Question

 

Answer 1

$(P\Rightarrow Q)\Rightarrow R =(P{}'+Q) \Rightarrow R= ((P{}'+Q) {}' + R)=PQ{}'+R$

Now check the option

a)$P\Rightarrow (Q\Rightarrow R)=P{}'+(Q\Rightarrow R)=P{}'+Q{}'+R\neq LHS$

b) $\Rightarrow$ is right associate (source https://en.wikipedia.org/wiki/Currying#Logic ) so it simplifies to option a)  that is $P\Rightarrow (Q\Rightarrow R)$ which is too incorrect. 
c)$P\Rightarrow Q V R=P{}'+(Q V R)=P{}'+Q+R \neq LHS$

so answer wil be D) 

Comments

$\large p\rightarrow q\rightarrow r\Leftrightarrow p\rightarrow\left ( q\rightarrow r \right )$

https://en.wikipedia.org/wiki/Currying#Logic

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updated !