The correct answer is (a) Belgaum.
The Konkan Railway is a 760-kilometre (470 mi) long coastal railway line in India that runs along the western coast of the country, connecting the states of Maharashtra, Goa, Karnataka, and Kerala. It was built between 1982 and 1998 and is one of the most scenic railways in the world.
The Konkan Railway does not connect Belgaum because the city is located in the northern part of Karnataka, while the Konkan Railway runs along the western coast of the country. Belgaum is also not connected to the Konkan Railway by any other railway line.
The other options, Madgaon, Ratnagiri, and Udupi, are all connected to the Konkan Railway. Madgaon is a city in Goa and is the headquarters of the Konkan Railway Corporation. Ratnagiri is a city in Maharashtra and is the second largest city in the Konkan region. Udupi is a city in Karnataka and is a popular tourist destination.