Concept: Culpable homicide and murder are related but not identical. Murder is a more serious form of culpable homicide.
Step 1: Check Assertion (A).
The assertion says every culpable homicide is murder. This is incorrect.
\[
\text{Every murder is culpable homicide, but every culpable homicide is not murder}
\]
Step 2: Check Reason (R).
Murder is an aggravated form of culpable homicide. This statement is correct.
\[
\text{Murder} = \text{Aggravated culpable homicide}
\]
Step 3: Choose the correct option.
Since Assertion is incorrect but Reason is correct, the correct answer is option (D).