The correct answer is: C. Rajatarangini
The Rajatarangini is a chronicle of the kings of Kashmir, written by Kalhana in the 12th century. It is considered to be one of the most important works of Sanskrit literature. The Rajatarangini is a valuable source of information about the history of Kashmir, and it is also a work of great literary merit.
The Spanda-Karika is a treatise on Kashmir Shaivism, written by Abhinavagupta in the 10th century. It is one of the most important texts on Kashmir Shaivism, and it is considered to be a classic of Hindu philosophy.
The Vartika is a commentary on the Yoga Sutras of Patanjali, written by Vyasa in the 2nd century BCE. It is one of the most important commentaries on the Yoga Sutras, and it is considered to be a classic of Hindu philosophy.
The Sivadrishti is a treatise on Kashmir Shaivism, written by Kshemaraja in the 11th century. It is one of the most important texts on Kashmir Shaivism, and it is considered to be a classic of Hindu philosophy.
The Rajatarangini is the earliest literary source of Kashmir because it was written in the 12th century, while the other texts were written in the 10th century, 2nd century BCE, and 11th century, respectively.