Explanation:

- mKisan is designed to deliver important agricultural information to farmers.

- Option 1: SMS - mKisan primarily uses the SMS service. It sends essential updates via text, making it accessible even to those without internet access.

- Option 2: Web - While important for other services, mKisan focuses on SMS for direct communication with farmers.

- Option 3: App - Apps require smartphones and data; mKisan targets wider reach via SMS.

- Option 4: E-mail - Useful for detailed communication, but farmers may not frequently check emails.

- Option 5: None of the above - Not applicable, as SMS is indeed the primary service.