Traditional occupations of many ST communities in Sikkim include:

Agriculture and animal husbandry
Hunting and gathering
Fishing
Trade and commerce

The correct answer is: a) Agriculture and animal husbandry.

Agriculture and animal husbandry are the traditional occupations of many ST communities in Sikkim. The main crops grown in Sikkim are rice, maize, wheat, barley, and potatoes. The main animals reared are cattle, yaks, goats, and sheep.

Hunting and gathering are not traditional occupations of ST communities in Sikkim. Fishing is a traditional occupation of some ST communities in Sikkim, but it is not as important as agriculture and animal husbandry.

Trade and commerce are not traditional occupations of ST communities in Sikkim.