Option 1: The Brahmaputra River - The Brahmaputra River does pass through the Kaziranga National Park. It is one of the major rivers in India and it flows through the park, providing water and sustenance to the diverse wildlife that inhabits the area.

Option 2: The Diphlu River - The Diphlu River does pass through the Kaziranga National Park. It is a tributary of the Brahmaputra River and flows within the park, adding to the overall biodiversity of the area.

Option 3: National Highway No. 37 - National Highway No. 37 does pass through the Kaziranga National Park. The highway is an important transportation route and it cuts through the park, leading to increased human activity and potential threats to the wildlife.

Option 4: Railway track of Indian Railway - This is the correct answer. The railway track of Indian Railway does NOT pass through the Kaziranga National Park. Unlike the other options, the railway does not intersect or cut through the park, allowing for a more undisturbed habitat for the wildlife.

In conclusion, the correct answer is option 4 as the railway track of Indian Railway does not pass through the Kaziranga National Park.