Step 1: Idea:
We will sort the four options into what each one really is, and the entrance will stand out from the rest.
Step 2: Name the type of each option:
Lahori Gate and Delhi Gate are gateways. Chatta Chowk is a roofed passage. River Side is a direction or side of the fort.
Step 3: Keep only the gateways:
The question asks for an entrance, so only Options 1 and 2 qualify. Chatta Chowk and River Side are removed.
Step 4: Choose between the two gates:
The passage uses the words 'main entrance' only with the Lahori Gate, so Option 1 wins.
Step 5: Remember the history:
The Lahori Gate faces Lahore and is the famous gate from which the national flag is hoisted on Independence Day. This matches.
Final Answer:
The Lahori Gate is the main entrance, so the answer is Option 1. \[ \boxed{\text{Lahori Gate}} \]
