Mathematics

Problem

The value of

\hat{i} \times (\vec{r} \times \hat{i}) + \hat{j} \times (\vec{r} \times \hat{j}) + \hat{k} \times (\vec{r} \times \hat{k})

is - (A)

\vec{r}

(B)

2\vec{r}

(C)

3\vec{r}

(D)

4\vec{r}