Political science & International Relations (PSIR) as an optional paper is a very scoring optional paper with little effort .This is the only optional fulfilling the need of UPSC requirements.I am saying this because PSIR optional gives intense opportunity to students to cover a large section of GS just by covering a single optional.
Following subjects of General Studies are covered under PSIR….
A.Indian Polity and Constitution (GS paper 2)
B.International Relations ( GS paper 2)
C.Modern Indian History & Post Independence India
D.Indian Society ( GS paper 1)
E.Ethics ( Almost all Thinkers) GS paper 4
F. Economy & Agriculture
Besides these One Essay topic is almost everyyear from political science & IR.
In civil services interview the questions from this subject is most alluring to Interview panel members.
If we talk About preliminary exam 40 questions are covered from this single optional.Indina Polity,IR (including Institutions & Modern Indian History)