In a clockwise system

In a clockwise system or left handed system $\widehat{j}\times \widehat{k}=\widehat{i}$

B, C,D are not correct

In clock wise system

$\widehat{i}\times \widehat{j}=\widehat{k}$

$\widehat{j}\times \widehat{k}=\widehat{i}$

$\widehat{k}\times \widehat{i}=\widehat{j}$

To have contrast between two systems where as it anticlockwise system or right handed system we have

We have using right hand rule

$\widehat{i}\times \widehat{j}=\widehat{k}$

$\widehat{j}\times \widehat{k}=\widehat{i}$

$\widehat{k}\times \widehat{i}=\widehat{j}$