Definitional contrast:
Consider each term separately. "Education" is the broader outcome of learning that may or may not result from an exchange, it describes a change in knowledge, not the act of exchanging it. "Technology transfer" is a narrower, one-directional handover of a specific innovation, typically from research institutions to farmers, and does not necessarily involve two-way sharing. "Farming" is simply the agricultural activity itself, unrelated to information exchange. Only "communication" describes the general, two-way process by which extension workers and farmers exchange ideas, feedback, and knowledge through any channel (demonstrations, meetings, media). Since the question asks specifically about the process of sharing information and knowledge, and not its outcome or a subtype of it, option (2) is correct.