Each crop in this question is best matched to the weed that shares its growing conditions. Echinochloa crus-galli, or barnyard grass, is the classic problem weed of rice because it thrives in the same waterlogged conditions rice needs. Euphorbia hirta is common in maize and other upland fields, Phalaris minor is the well-known dominant weed of wheat across the Indo-Gangetic plains, and Lantana camara is a woody shrub that typically takes over bare or waste land rather than cultivated fields.
Putting these pairs together gives Rice-Echinochloa, Maize-Euphorbia, Wheat-Phalaris, and Bare land-Lantana, which lines up with option 3.