The correct answer is option 1, Vishakhapatnam. A land-locked harbor is a harbor or port that is completely surrounded by land and does not have direct access to the open sea. Vishakhapatnam is situated on the eastern coast of India in the state of Andhra Pradesh. It is located between the Eastern Ghats and the Bay of Bengal. Unlike the other options, Vishakhapatnam does not have a direct connection to the open sea, which makes it a land-locked harbor.

Option 2, Ennore, is a major port located on the eastern coast of India in Tamil Nadu. It has direct access to the Bay of Bengal.

Option 3, Mumbai, is situated on the western coast of India in Maharashtra. It is a natural harbor with direct access to the Arabian Sea.

Option 4, Haldia, is a major port located on the eastern coast of India in West Bengal. It is connected to the Bay of Bengal through the Hooghly River.

Therefore, the correct answer is Vishakhapatnam, as it is the only option that fits the definition of a land-locked harbor.