Well, Economics can be a very safe optional in mains for those who have economics or commerce background. As the syllabus of economics for prelims is relatively concise and can be covered in a short span of time and the cut off is also reasonable. But students from non-economics background should avoid this optional because there is hardly any good coaching available, so they may find it difficult".

Other optional subjects are as following:
Maithili
Russian
Hindi
English Qualifying for IAS Exams
Zoology
Assamese
Mathematics subjects for IAS Exams
Kashmiri
Manipuri
Indian History
English
Agriculture
Bengali
Urdu
Philosophy
Kannada
Konkani
Geography
Animal Husbandry and Veterinary Science
Tamil
French
Mechanical Engineering
Persian
Sanskrit
Essays for IAS Exams
Chinese
Pali
Statistics
Marathi
Gujarati
Geology
Oriya
Chemistry
Sociology
Bodo
Law
Political Science
Electrical Engineering
Economics
Physics
Commerce
General Studies for IAS Exams
Botany
Indian Languages for IAS Exams
Telugu
Santali
Anthropology
Public Administration
Nepali
Malayalam
German
Psychology
Management
Dogri
Sindhi
Civil Engineering
Medical Science
Punjabi