$\begin{array}{lcl} \textbf{Assertion [a]} &: & \text{At a manhole, the crown of the outgoing sewer should not be higher} \\ & & \text{than the crown of the incoming sewer.} \\ \textbf{Reason[r]} & :& \text{Transition from a larger diameter incoming sewer to a smaller diameter } \\ & & \text{outgoing sewer at a manhole should not be made.} \end{array}$

The $\textbf{CORRECT}$ option evaluating the above statements is

Both $\textbf{[a]}$ and $\textbf{[r]}$ are true and $\textbf{[r]}$ is the correct reason for $\textbf{[a]}$

Both $\textbf{[a]}$ and $\textbf{[r]}$ are true and $\textbf{[r]}$ is not the correct reason for $\textbf{[a]}$

Both $\textbf{[a]}$ and $\textbf{[r]}$ are false

$\textbf{[a]}$ is true but $\textbf{[r]}$ is false