Explanation

Genetically modified crops carry modified genetic material because new DNA is introduced into the genome (1), as in Bt cotton carrying the cry gene, or because existing DNA is removed or disrupted (2), as in gene-knockout lines. The practical outcome is the introduction of new traits (4), such as pest resistance or herbicide tolerance. The mere introduction of RNA (3), without any change to the DNA, does not constitute modification of the genetic material in the sense used here. Statements 1, 2 and 4 are correct, option (D).