Concept:Agricultural marketing boards perform marketing functions; they do not carry out production activities such as harvesting.
Explanation:The first activity, price stabilization within seasons, is a core function of marketing boards because they help reduce price fluctuations for farmers and buyers.
The second activity, harvesting of farm produce, is a farming or production activity, not a marketing function, so it is not correct.
The third activity, grading and standardization of produce, is a key marketing board function that ensures quality control and uniform product classification.
The fourth activity, market research for produce, is also a marketing board function because it helps identify market trends and consumer demand.
Therefore, the valid functions are I, III, and IV only.
Answer:D. I, III and IV only