1. Region: region (defined by physical position and average rainfall) in which each paddock is located. 2. Position: geographic position of each paddock in the general area according to the compass directions (E = east, W = west, N = north, S = south, C = central). 3. Area: size of the paddock in hectares. 4. Age: years elapsed since the paddock was plowed out and planted with new sugarcane seeds. 5. HarvestMonth: month of the year in which the harvest took place (1 = January, 2 = February, etc.). 6. HarvestDuration: time taken to harvest the sugarcane in days. 7. Tonn.Hect: tons per hectare of sugarcane produced by this paddock. 8. Sugar: commercial sugar content produced by this paddock (in tons per batch processed). 9. Rainfall.96: Total rainfall for the district from July 1996 through December 1996 (millimeters).

I need to build a best linear model in rstudio to develop an explanatory model for the "Tonn/Hect" response variable relating to the other variables that influence growth. Which variable should I include to build a linear model?

I just need an idea, not a specific answer.