The correct options are
A Abundant rainfall
B Moderately thick layers of alluvial soil in river basins
C Laterite soil along hilly tracts
Abundant rainfall, moderately thick layers of alluvial soil in the river basins, and laterite soil along the hilly tracts are the favourable geographical factors for the crop diversity in the midland region. This region is suitable for the cultivation of rubber, which is a chief commercial crop of Kerala.