Step 1: Read what is being asked.
The question wants the house that is treated as the highest in our Parliamentary system. So we must look at the two houses of Parliament and decide which one holds the senior, more permanent position.
Step 2: Recall the two houses.
India has a two-house Parliament. The Lok Sabha is the lower house, also called the House of the People. The Rajya Sabha is the upper house, also called the Council of States.
Step 3: Check the options one by one.
Assembly and National Council are state or general terms, not houses of the Union Parliament, so we drop them. That leaves Lok Sabha and Rajya Sabha.
Step 4: Understand why Rajya Sabha is called the upper house.
In a Parliamentary system the upper house is the one that gives stability. The Rajya Sabha is a permanent body that is never fully dissolved. Members retire in parts, so the house always keeps running.
Step 5: Note its special status.
The Vice President of India is the Chairman of the Rajya Sabha. Senior members and experts often sit here, which adds to its high standing. Because it is the upper, permanent house, it is regarded as the highest house.
Step 6: Match with the options.
So the correct choice is the third option, Rajya Sabha.
\[ \boxed{\text{Rajya Sabha}} \]