In Indian geography and tourism, the spectacular Dudh Sagar Waterfalls are a famous tourist attraction; this question asks you to identify in which Indian state the Dudh Sagar Waterfalls are located.

Introduction / Context:
Dudh Sagar Waterfalls is one of the most photographed waterfalls in India and often appears in travel magazines, films, and railway tourism brochures. Because it lies near a state border and is approached by train routes, exams like to test whether candidates know the correct host state. This makes it a classic static geography question that rewards attentive reading of maps and travel information.

Given Data / Assumptions:
The water body mentioned is Dudh Sagar Waterfalls, sometimes spelled Dudhsagar.
The options are Goa, Bihar, Uttar Pradesh, and a generic option "None of the above".
We assume the question refers to the commonly accepted administrative location of the main waterfall site.

Concept / Approach:
Dudh Sagar Waterfalls lie on the Mandovi River and are located on the border between Goa and Karnataka. However, administratively the famous viewing and tourism access point is within Goa, and standard GK sources list the falls under Goa tourism. Exam preparation books therefore treat Goa as the correct state. The task is to link the name Dudh Sagar with Western Ghats and then with Goa.

Step-by-Step Solution:
Step 1: Recall that Dudh Sagar Waterfalls are in the Western Ghats on the Mandovi River. Step 2: Remember popular images of Dudh Sagar where trains pass close to the falls along the Goa route. Step 3: Associate the Mandovi River and this waterfall with Goa, which promotes it as a key tourist attraction. Step 4: Check the given options and identify Goa as the only plausible coastal Western Ghats state among them. Step 5: Select Goa and reject other options since they are far from the Western Ghats region.

Verification / Alternative check:
State tourism portals and Indian Railways tourism packages both advertise Dudh Sagar as a major attraction of Goa. Maps of the Western Ghats also show the falls within the boundaries of Goa, near the Karnataka border. There is no reference connecting this waterfall with Bihar or Uttar Pradesh, which are in the Indo Gangetic plain, far from this area.

Why Other Options Are Wrong:
Bihar: A state in eastern India, mostly in the plains of the Ganga basin, with no location that matches the Western Ghats waterfall known as Dudh Sagar.
Uttar Pradesh: A northern plains state famous for cities like Lucknow and Varanasi, again not linked with the Western Ghats or coastal waterfalls like Dudh Sagar.
None of the above: This can be eliminated because Goa is a correct and well documented answer, so the generic option is not appropriate here.

Common Pitfalls:
Some learners confuse Dudh Sagar with other waterfalls having similar names or believe that because it is near a state border the exam might be trying to trick them with "None of the above". Others may not connect the Mandovi River with Goa. A reliable strategy is to remember that popular images of Dudh Sagar show Goa railway routes and to link it firmly with Goa tourism in your long term memory.

Final Answer:
Dudh Sagar Waterfalls are located in the Indian state of Goa.