The extension method that will benefit only the literate farmers is

The extension method that will benefit only the literate farmers is newspapers. This is because newspapers are primarily a written medium, and so farmers who are literate and can read and understand the information presented in the newspaper will benefit from it. On the other hand, farmers who are not literate may struggle to benefit from newspapers, as they may not be able to read the information or understand it fully. Radio and television may be more accessible to illiterate farmers, as they are primarily audio-visual mediums, and demonstration may be a more hands-on approach that does not rely on reading or writing skills.