The question asks to identify the correct statements regarding different Crop Evapotranspiration (ET) estimation methods.

Method Accuracy Assessment

Let's evaluate each statement:

• A. Modified Blaney Criddle method is only temperature based: This is incorrect. The Blaney-Criddle method uses mean monthly temperature and the percentage of annual daylight hours. It is not solely based on temperature.
• B. Modified Penman Monteith method requires more climate data: This is correct. The Penman-Monteith method is a physically-based approach and requires comprehensive climate data, including solar radiation, air temperature, humidity, and wind speed, making it more data-intensive than simpler methods.
• C. Thornthwaite method is based on temperature data: This is correct. The Thornthwaite method primarily relies on mean monthly temperature data to estimate potential evapotranspiration.
• D. Crop coefficient is multiplied to get reference evapotranspiration by Pan evaporation method: This is incorrect. The Pan evaporation method uses a pan coefficient ($K_p$) multiplied by pan evaporation ($E_{pan}$) to estimate reference evapotranspiration ($ET_o$). The crop coefficient ($K_c$) is then used to adjust $ET_o$ to estimate crop evapotranspiration ($ET_c$).
• E. Radiation method requires air temperature and sunshine radiation: This is correct. Methods like the Hargreaves-Samani equation, which fall under radiation-based approaches, utilize temperature data (mean, max, min) and estimates of solar radiation (often derived from sunshine hours).

Conclusion on Correct Statements

Based on the analysis, statements B, C, and E are correct.

Final Answer Selection

The combination of correct statements is B, C, and E.

Therefore, the correct option is 4.