The correct options are
A Somdeva's "Kathasaritsagara"
B Kalhana's "Rajtarangini"
One reason that makes Somdeva's "Kathasaritsagara" and Kalhana's "Rajtarangini" unique is that they were written in Kashmir. They are also considered to be the first historical books of India. Among the two, "Kathasaritsagara" is the oldest.