The correct answer is A) Dolmens.
A dolmen is a type of megalithic tomb consisting of a large flat stone supported by two or more upright stones. Dolmens are found in many parts of the world, including Europe, Asia, Africa, and the Americas. In Kerala, dolmens are found in the districts of Palakkad, Malappuram, and Thrissur.
Stelae are upright stone slabs or pillars, often inscribed with writing or carved with images. Stelae are found in many parts of the world, including Europe, Asia, Africa, and the Americas. In Kerala, stelae are found in the districts of Kannur, Kasaragod, and Wayanad.
Cromlechs are stone circles, often enclosing a dolmen or other type of megalithic monument. Cromlechs are found in many parts of the world, including Europe, Asia, Africa, and the Americas. In Kerala, cromlechs are found in the districts of Palakkad, Malappuram, and Thrissur.
Obelisks are tall, four-sided stone monuments with a pyramidal top. Obelisks are found in many parts of the world, including Egypt, Greece, Rome, and China. In Kerala, obelisks are not found.