Consider the following Assertion $(A)$ and Reason $(R)$:
Assertion $(A)$: The two lines $\bar{r}=\bar{a}+t(\bar{b})$ and $\bar{r}=\bar{b}+s(\bar{a})$ intersect each other.
Reason $(R)$: The shortest distance between the lines $\bar{r}=\bar{p}+t(\bar{q})$ and $\bar{r}=\bar{c}+s(\bar{d})$ is equal to the length of the projection of the vector $(\bar{p}-\bar{c})$ on $(\bar{q} \times \bar{d})$.
The correct answer is:

• A
  Both $(A)$ and $(R)$ are true and $(R)$ is the correct explanation of $(A)$
• B
  Both $(A)$ and $(R)$ are true and $(R)$ is not the correct explanation of $(A)$
• C
  $(A)$ is true,but $(R)$ is false
• D
  $(A)$ is false,but $(R)$ is true