The correct answer is option 3: Tuticorin. Tuticorin is not a part of the western coast of India.
Option 1: Nhava Sheva is located in Maharashtra and is one of the busiest ports on the western coast of India. It is a significant part of the western coast.
Option 2: Marmagao is in Goa and is also a major port on the western coast of India. It is an important part of the western coast.
Option 4: Kochi is in Kerala and is a major port and city on the western coast of India. It is also a significant part of the western coast.
Therefore, it can be concluded that Tuticorin is the only option that is not a part of the western coast of India.