Veliconda group of low hills is a structural part of the Eastern Ghats. The Eastern Ghats is a mountain range that runs parallel to the eastern coast of India. It extends from West Bengal in the north to Tamil Nadu in the south. The Veliconda hills, also known as the Velikonda Range, are a part of this mountain range.

Option 1, Nilgiri Hills, is incorrect because the Nilgiri Hills are located in the Western Ghats. The Western Ghats is a mountain range that runs parallel to the western coast of India.

Option 2, Western Ghats, is incorrect because the Veliconda hills are not a part of the Western Ghats. The Western Ghats is a separate mountain range.

Option 4, Cardamom Hills, is also incorrect because the Cardamom Hills are located in the Western Ghats.

Therefore, the correct answer is option 3, Eastern Ghats, as the Veliconda hills are a structural part of this mountain range.