The Cardamom Hills in India are regarded as a continuation of the Western Ghats.

The Eastern Ghats, mentioned in option 1, are a separate mountain range located to the east of the Deccan Plateau. They run parallel to the Bay of Bengal and are not connected to the Cardamom Hills. Option 1 is therefore incorrect.

The Mizo Hills, mentioned in option 2, are a mountain range located in the state of Mizoram in Northeast India. They are also not connected to the Cardamom Hills and option 2 is incorrect.

The Naga Hills, mentioned in option 3, are a mountain range located in the state of Nagaland in Northeast India. They are again not connected to the Cardamom Hills, making option 3 incorrect.

Option 4, Western Ghats, is the correct answer. The Western Ghats are a mountain range that runs parallel to the western coast of India, stretching from Gujarat in the north to Tamil Nadu in the south. The Cardamom Hills are located in the southern part of the Western Ghats and are considered a continuation of this mountain range.

Therefore, the correct answer is option 4.