Which of these are most widely used in genetic engineering?

Plastids are semiautonomous cell organelles. They take part in storage and synthesis of organic compounds. Mitochondria are called the power houses of the cell as they are the centres of Kreb's cycle of respiration liberating the maximum amount of energy. Ribosomes are submicroscopic cell organelles manufacturing protein. Plasmids are defined as autonomous elements, whose genomes exist in the cell as the extrachromosomal unit. These are the chromosomal elements found in bacteria. Plasmids are used as cloning vectors due to their increased yield potential.