Correct Answer: (d) Amarkosha
Note: Amarkosha was written by Amarsimha. Varahamihira has written Panchasiddhantika, Brihat Samhita and Brihat Jataka.
Amarsingh was the author of Amarkosha. Amara seems to have been a Buddhist and most of his work was destroyed with the exception of what is the celebrated Amara-Kosha Treasury of Amara a vocabulary of Sanskrit roots in three books and hence sometimes called Trikanda or the "Tripartite". It is also known as "Namalinganushasana"
Panchasiddhantika is a Sanskrit book on astronomy written by Varahamihira in the 6th century CE. The book summarizes five earlier astronomical treatises and is considered a valuable resource for scholars of Indian astronomy. The book summarizes the contents of five earlier astronomical treatises by five authors: Surya Siddhanta, Romaka Siddhanta, Paulisa Siddhanta, Vasishtha Siddhanta, and Paitamaha Siddhant