Step 1: Recall the three sectors.
The primary sector covers activities that use natural resources directly, like farming, fishing, and mining. The secondary sector covers manufacturing. The tertiary sector covers services that support the other two, like banking, transport, and education.
Step 2: Place agriculture correctly.
Agricultural production depends directly on land and natural resources, so it belongs to the primary sector, not the tertiary sector. This makes the Assertion false.
Step 3: Check the Reason on its own.
The tertiary sector is indeed called the service sector because it provides support services rather than producing goods directly, so the Reason is true by itself.
Step 4: Combine and conclude.
Since the Assertion is wrong but the Reason is a correct fact, the answer is option (D): Assertion is false, Reason is true.