The correct answer is (c) Kalsi.
The Kalsi inscription is a rock edict of the Mauryan emperor Ashoka, inscribed on a rock face near the town of Kalsi in the Indian state of Uttarakhand. It is dated to the 3rd century BCE and is one of the earliest surviving examples of writing in the Brahmi script. The inscription records Ashoka’s conversion to Buddhism and his efforts to promote the spread of the religion.
The Baijnath inscription is a Sanskrit inscription found in the Baijnath temple complex in the Indian state of Himachal Pradesh. It is dated to the 10th century CE and records the construction of the temple by the king of Kashmir, Ananta Deva.
The Palethi inscription is a Sanskrit inscription found in the Palethi village in the Indian state of Uttarakhand. It is dated to the 11th century CE and records the construction of a temple by the king of Kanauj, Harshavardhana.
The Pandukeshwar inscription is a Sanskrit inscription found in the Pandukeshwar village in the Indian state of Uttarakhand. It is dated to the 12th century CE and records the construction of a temple by the king of Kashmir, Jayasimha.
The Kalsi inscription is the oldest of these inscriptions and is therefore the correct answer to the question.