Step 1: Understanding the question.
Primary activities refer to the extraction or collection of natural resources, such as agriculture, fishing, mining, and forestry.
Step 2: Analyzing the options.
(A) कृषि: Correct — Agriculture is a primary activity because it involves the cultivation of crops and livestock rearing.
(B) वानिकी: This is incorrect, as forestry is considered a primary activity but agriculture is more directly related to primary activities.
(C) औद्योगिक: This is incorrect, as industrial activities fall under secondary activities.
(D) इनमें से सभी: This is incorrect, as only agriculture is the most direct primary activity in this list.
Step 3: Conclusion.
The correct answer is (A) कृषि, as agriculture is a primary activity.