Option c is the correct answer. Kshapanak was an ancient Indian astronomer and astrologer who was one of the Nine Gems of Chandragupta II. His important works is Jyothisyashastra. His other work in lexicography and poem called Dvatrishatika. The Nine Gems were a group of scholars, artists, and ministers who adorned the court of Chandragupta and contributed to his glory and success. The other gems are Dhanvantri, Amarasimha, Vararuchi, Sanku, Vetala Bhatta, Ghatakarpara, Kalidasa and Varahmihra.